novel technologies for indicator mineral-based...
TRANSCRIPT
23
NOVEL TECHNOLOGIES FOR INDICATOR MINERAL-BASED EXPLORATION
byMarja Lehtonen1*), Yann Lahaye1, Hugh O’Brien1), Sari Lukkari1),
Jukka Marmo1) and Pertti Sarala2)
Lehtonen, M., Lahaye, Y., O’Brien, H., Lukkari, S., Marmo, J. & Sarala, P. 2015. Novel technologies for indicator mineral-based exploration. Geological Survey of Finland, Special Paper 57, 23−62, 9 figures, 6 tables and 4 appendices.
New mineralogical and geochemical methods for till sampling-based exploration were developed at the Geological Survey of Finland (GTK) during the TEKES-funded project “Novel technologies for greenfield exploration (NovTecEx)”. The techniques are based on recently installed analytical instruments at the Finnish Geosciences Research Laboratory (SGL), a high-resolution single collector induc-tively coupled mass spectrometer for trace element analysis (HR-SC-ICPMS) and field emission SEM for automated electron optics (FE-SEM-EDS). The sample ma-terial comprised till samples collected in the Savukoski-Pelkossenniemi study area in eastern Lapland during another NovTecEx subproject in which different drill-ing techniques were tested for sampling. The heavy mineral concentrates of the till samples were produced by optimizing conventional processing methods to meet the requirements of modern research instruments. The fully digested concentrates were analysed by HR-SC-ICPMS to detect interesting trace element concentrations and screen the samples for detailed FE-SEM-EDS. The resulting processing and analytical protocols can be applied in the exploration of various types of deposits. The results demonstrate that the use of modern research instruments can reduce the sample size needed for indicator mineral studies. The mineralogical and geo-chemical results from the eastern Lapland samples reflect the large and diversified provenance area.
Keywords (GeoRef Thesaurus, AGI): till, sampling, mineralogy, geochemistry, methods, analysis, indicator minerals, mineral exploration, Savukoski, Pelkosen-niemi, Finland
1) Geological Survey of Finland, P.O. Box 96, FI-02151 Espoo, Finland2) Geological Survey of Finland, P.O. Box 77, FI-96101 Rovaniemi, Finland*) corresponding author, e-mail: [email protected]
Novel technologies for greenfield explorationEdited by Pertti SaralaGeological Survey of Finland, Special Paper 57, 23–62, 2015
24
Geological Survey of Finland, Special Paper 57Marja Lehtonen, Yann Lahaye, Hugh O’Brien, Sari Lukkari, Jukka Marmo and Pertti Sarala
INTRODUCTION
The basis of this study was a TEKES-funded 3-year (2012–2014) project, “Novel technologies for greenfield exploration”, or “NovTecEx” in short. The Research Laboratory of the Geological Survey of Finland (GTK) was responsible for NovTecEx subproject 2, entitled “Mineralogical study of till”. The international collaborative partner in this pro-ject was the Geological Survey of Canada (GSC).
The aim of the subproject was to develop new, cost- and time-efficient methods for processing exploration till samples and investigating their mineralogical composition for ore potential. The goal was to be able to detect extremely small quantities of indicator minerals from a range of mineralization types and to subsequently quanti-tatively analyse them by a combination of mod-ern geochemical and electron optical methods. The most commonly used indicator minerals are listed in Table 1. The development relied on re-cently (2013) installed analytical facilities at the Finnish Geosciences Research Laboratory (SGL), a high-resolution single collector inductively cou-pled mass spectrometer for trace element analysis (HR-SC-ICPMS) and a field emission scanning electron microscope for automated electron optics (FE-SEM-EDS).
The sample material consisted of till samples collected in eastern Lapland (Fig. 1). For this pro-ject, the main focus was on processing and analysis of the fine fraction of till (<63 μm), because this is
the most likely material to contain indicator min-erals relevant to the exploration area (e.g. gold, platinum group minerals and REE minerals; Table 1). This is due to the exponentially higher num-ber of individual mineral grains in the fine frac-tion relative to the coarse fraction, and also due to the expected grain size of indicators from this area. For these reasons, the till fine fraction has also conventionally been used as a sample medium for geochemical investigations (e.g. Koljonen et al. 1992, and references therein).
The majority of the indicator minerals have significantly higher densities (Table 1) than the minerals that make up the vast majority of till materials (e.g. quartz and feldspar), and they can consequently be concentrated using gravity-based methods. The indicator mineral method as such is a long-established and conventionally used ex-ploration method (cf. Peuraniemi 1990, Stendal & Theobald 1996). An important aspect in this study was the establishment of a processing protocol to effectively concentrate even the finest heavy min-eral fraction without significant indicator grain loss. The next step was to develop a cost- and time-efficient method to analyse the trace element chemistry of the concentrates in order to identify samples of interest. Finally, the indicator minerals were to be identified and analysed from these se-lected samples using automated electron optics.
SAMPLING AREA AND GEOLOGICAL SETTING
The NovTecEx study area is located in the Savukos-ki-Pelkosenniemi district in eastern Lapland (Fig. 1) and covers about 980 km2 in total. The heavy
mineral samples were collected in an 850 km2 area, since sampling was not possible in the Akanvaara claim and the Sakkala-aapa mire areas.
Bedrock geology
Lithologically, the Savukoski-Pelkosenniemi study area is divided into two main domains: Archaean and Palaeoproterozoic. The bedrock in the east-ern part of the area is composed of granite gneiss with greenstones of the Archaean basement. In the west, the bedrock consists of metasedimen-tary rocks with narrow mafic volcanic and diabase veins of the Palaeoproterozoic Central Lapland Greenstone Belt (Lehtonen et al. 1998). The main domains are separated by a N–S-oriented chain of
komatiite and graphite sulphide schists. The Akan-vaara layered intrusion with a known chromite-PGE mineralization is located in the SE part of the study area (Mutanen 1997). There is no knowl-edge of other economically significant mineraliza-tions in the area, but there is potential for various types of deposits, including gold, base metals and so-called high-tech metals (e.g. Nb, Ta and REE) (e.g. Sarapää et al. 2013).
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Geological Survey of Finland, Special Paper 57Novel technologies for indicator mineral-based exploration
Commodity / Deposit
Indicator minerals
Chemical composition
Average density (gcm-3)
Typical size range (mm)
Diamond1 Cr-pyrope garnet (Mg,Fe)3(Al,Cr)2(SiO4)3 3.7 0.25-0.5
Eclogitic garnet (Fe++,Mg)3Al2(SiO4)3 4.0 0.25-0.5
Mg-ilmenite (Fe++,Mg)TiO34.7 0.25-0.5
Cr-diopside CaMg(Fe,Cr)Si2O6 3.3 0.25-0.5
Chromite (Fe++, Mg)(Cr,Al)2O4 4.8 0.25-0.5
Forsteritic olivine (Mg,Fe)2SiO4 3.3 0.25-0.5
Diamond C 3.5 0.25-0.5Gold2 Gold Au 17.6 0.01-0.25
Scheelite CaWO4 6.0 0.01-0.25
Rutile TiO2 4.3 0.01-0.25
Sulphides >4.0 0.01-0.25
Magmatic Ni-Cu-PGE3 Cr-diopside CaMg(Fe,Cr)Si2O6 3.3 0.25-2.0
Forsteritic olivine (Mg,Fe)2SiO4 3.3 0.25-2.0
Enstatite (Mg,Fe)2Si2O6 3.2 0.25-2.0
Chromite (Fe++, Mg)(Cr,Al)2O4 4.8 0.25-2.0
Pentlandite (Fe,Ni)9S8 4.8 0.01-0.25
Pyrrhotite Fe(1-x)S (x=0-0.17) 4.6 0.01-0.25
Chalcopyrite CuFeS2 4.2 0.01-0.25
Pyrite FeS2 5.0 0.01-0.25Platinum group minerals (PGM)
>8.0 0.001-0.1
VMS deposits4 Chalcopyrite CuFeS2 4.2 0.01-0.25
Galena PbS 7.4 0.01-0.25
Sphalerite (Zn,Fe)S 4.1 0.01-0.25
Pyrrhotite Fe(1-x)S (x=0-0.17) 4.6 0.01-0.25
Pyrite FeS2 5.0 0.01-0.25
Gahnite (Zn,Fe)Al2O4 4.3 0.25-2.0
Spessartine (Mn++,Fe)3Al2(SiO4)3 4.2 0.25-2.0
Staurolite (Fe++,Mg)2Al9(Si,Al)4O20(O,OH)4 3.7 0.25-2.0
Pb-Zn deposits5 Galena PbS 7.4 0.01-2.0
(Mississippi Valley type) Sphalerite (Zn,Fe)S 4.1 0.01-2.0
Porphyry Cu deposits6 Sulphides > 4.0 0.25-2.0
Andradite Ca3Fe+++2(SiO4)3 3.9 0.25-2.0
Diaspore AlO(OH) 3.4 0.25-2.0
Barite BaSO4 4.5 0.25-2.0
Alunite KAl3(SO4)2(OH)6 2.7 0.25-2.0
Dravite NaMg3Al6(BO3)3Si6O18(OH)4 3.1 0.25-2.0
Apatite Ca5(PO4)3(OH,F,Cl) 3.2 0.25-2.0
W-Mo deposits7 Scheelite CaWO4 6.0 0.01-0.25
Wolframite (Fe,Mn)WO4 7.3 0.01-0.25
Sulphides >4.0 0.01-0.25
Bi minerals >6.0 0.01-0.25
”High tech metals” Pyrochlore (Na,Ca)2Nb2O6(OH,F) 5.3 0.01-0.25
e.g. Nb, Ta, REE Columbite Fe++Nb2O6 6.3 0.01-0.25Ta-minerals >8.0 0.01-0.25
Allanite (Ce,Ca,Y)2(Al,Fe+++)3(SiO4)3(OH) 3.75 0.01-0.25
References:1. McClenaghan & Kjarsgaard (2007) 2. McClenaghan & Cabri (2011) 3 and 6. Averill (2011) 4. Averill (2001) 5. Oviatt et al. (2013) 7. McClenaghan et al. (2013)
Table 1. The most commonly used indicator minerals. Modified from McClenaghan (2013).
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Geological Survey of Finland, Special Paper 57Marja Lehtonen, Yann Lahaye, Hugh O’Brien, Sari Lukkari, Jukka Marmo and Pertti Sarala
Fig. 1. The Savukoski-Pelkossenniemi study area in eastern Lapland, where the NovTecEx till samples were collected. Contains data from the National Land Survey of Finland Topographic Database 03/2013.
Surficial geology
Northern Finland was at the centre of the latest continental glaciations by the Scandinavian ice sheet (Johansson et al. 2011). The central Lapland area belongs to the latest ice-divide zone of the Late Weichselian glaciation, where the glacier has had only a low erosional effect on the bedrock (Hirvas 1991, Johansson et al. 2011). Earlier knowledge of the surficial deposits and the glaciogenic for-mations in the study area is mainly based on re-search carried out during the 1970s by Hirvas et al. (1977) and the 1990s by Johansson (1995). During
these investigations, it was established that in the Savukoski-Pelkosenniemi area the till units were formed during three glacial phases, with a north-ern ice-flow direction during the oldest phase and northwestern and western directions during the middle and younger phases, respectively. The ice flow directions reflect the glacial transport and thus the possible provenance area for till.
Based on new observations during this project, glacial overburden is dominant in the study area (Sarala 2015). Sandy, matrix-dominant till is the
27
Geological Survey of Finland, Special Paper 57Novel technologies for indicator mineral-based exploration
main sediment type, having a thickness of 2–5 m in the higher ground and 5–15 m in the lowland areas. In the Kemijoki River valley, the thickness of sediment deposits is usually greater than in the other areas due to a bedrock shear or weakness zone underlying the river. The basal parts of the valley deposits are glaciogenic in origin, but the uppermost sediments have been deposited during post-glacial fluvial processes. The deepest thick-ness of the overburden based on drilling is more
than 50 m in the northern part of the study area. The sediments in the deepest drill hole were most-ly composed of sand and gravel, but layers of till were also observed. Under the Quaternary depos-its, the bedrock surface is commonly weathered, ranging from some centimetres up to several tens of metres, being mainly of the saprock type (frac-tured and partly weathered) and rarely saprolite (profoundly weathered) (cf. Sarala & Ojala 2008).
METHODS
Sampling
Heavy mineral samples were collected using test pit excavations and soil drilling using variable drilling techniques (soil drilling with a core diam-eter of 7–8 cm, soil drilling with ship sampling and reverse circulation (RC) drilling). The number of sampling sites was 157 (71 test pits + 86 drilling sites), resulting in a sampling density of about 1 sample per 5.5 km2.
The sampling strategy was to take the till sam-ples from the basal part of the till cover, about 1–2 m above the bedrock surface. This layer was thought to generally represent the same type of glacial deposition and transport history through-out the study area. At the same time, it allowed the
direct influence of the underlying bedrock sur-face on the samples to be avoided, i.e. the sampled till had been transported some distance from its source, representing a larger bedrock area.
Two types of samples were collected. The first were approximately five-litre till samples that rep-resented a one-metre soil drill core (core diam-eter 7–8 cm) or were collected from the test pits as one-metre-thick vertical profiles imitating the drilled samples (Fig. 2). The second sample type was a more conventional type of till sample with a volume of 12 litres and approximately 20–25 kg in weight. These were used as a reference for the equal-sized exploration samples.
Fig. 2. Sampling strategy for the till samples using soil drilling and test pit excavations.
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Geological Survey of Finland, Special Paper 57Marja Lehtonen, Yann Lahaye, Hugh O’Brien, Sari Lukkari, Jukka Marmo and Pertti Sarala
Sample processing and laboratory protocols
Prior to working on real samples, a large 200-kg sample of basal till was excavated in the Ilomantsi area, Eastern Finland, to obtain test material for process development. The chemical and mineral-ogical composition of basal till in the area is well known because of GTK’s previous heavy mineral surveys (Lehtonen et al. 2011). Testing of preconcentration methods
The starting point for establishing the sample pro-cessing protocol for the NovTecEx till samples was to reassess GTK’s routinely used processing meth-ods in order to meet the requirements of modern mineralogical research instruments. The tradi-tional processing methods were developed dur-ing a time when the main mineralogical research method was optical microscopy, which is rarely quantitatively possible for grain sizes below 0.25 mm. There are only a small number of exceptions, including the rare ultra heavy minerals such as gold and PGM, which can be effectively concen-trated and manually picked out even from grain sizes down to 15–20 microns. Presently, however, scanning electron microscopes and microprobes can automatically analyse the entire range of min-eralogy, even down to the submicron scale.
Testing was carried out on the Ilomantsi test sample employing the two preconcentration meth-ods most often used by GTK, the Knelson concen-trator and the shaking table (Wilfley table). The Knelson concentrator has been used at GTK for over two decades to process diamond and gold ex-ploration samples, in particular. The concentrator has been modified with add-ons to ensure better recovery of diamond indicator minerals (0.25–0.5 mm) (Chernet et al. 1999). The advantages of the method are efficiency, the standardized procedure, the minimal contamination risk and the standard size of the concentrate. The disadvantages include the large original sample size (10 kg), breakage of fragile mineral grains during processing, problems in concentrating sorted sediments lacking a clay fraction, and the recovery of fine-grained (<100 µm) moderately heavy minerals (density ~ 3.5–4.0 g·cm-3). The advantage of the shaking table is the user-specific procedure, which allows a skilled op-erator to influence the size and density of the pre-concentrate. During the tabling, there is also less breakage of fragile mineral grains. A disadvantage
is the overflow of flaky and platy heavy minerals, such as baddelyite. The preconcentration results for the Ilomantsi sample (Table 2) clearly dem-onstrated that the shaking table more efficiently recovers fine-grained heavy minerals, which was a crucial aspect in the project and the reason for choosing this method for the NovTecEx samples.
Separation methods
Subsequent laboratory methods involved standard heavy media separation (HMS) using methylene-di-iodide (3.3 g·cm-3), sieving and low intensity magnetic separation (LIMS). HMS was carried out using a centrifuge in order to intensify the sepa-ration of fine mineral grains (<250 µm). Table 3 presents the mineralogical composition of heavy and light mineral fractions of the test material, representing three different grain-size classes. The results for each grain size are combined from ten individual subsamples, and their mineralogy was determined by an automated SEM-EDS technique (see section Analytical methods). The mineral species of the light and heavy density fractions are highlighted in Table 3, and indicate that the sepa-ration process is very effective.
Nevertheless, there are some problems that are particularly related to separating the finest grained heavy minerals. Figures 3a and 3b are backscat-tered electron images (BSE) of <63 µm light and heavy mineral fractions. In Figure 3b there are sev-eral bright grains, mostly Fe and Fe-Ti oxides that are less than 10 µm in diameter. Based on their spe-cific gravity, they should have been included with the heavy mineral concentrate, but as they are so small they had been trapped by larger light mineral grains. When compared with the total amount of heavy minerals in the entire sample, these trapped grains constitute only 5–10%, but they selectively represent the finest grained portion of the heav-ies. This may be significant for minerals that ex-clusively occur in the very fine-grained fraction. Consequently, it is important to regularly monitor the process by also analysing light mineral frac-tions and unprocessed samples.
Based on the tests performed on the Ilomantsi reference material, a processing flow sheet for the NovTecEx samples was generated, as presented in Figure 4.
29
Geological Survey of Finland, Special Paper 57Novel technologies for indicator mineral-based exploration
Tabl
e 2.
Pre
conc
entr
atio
n re
sults
for t
he Il
oman
tsi t
est s
ampl
e.
Sam
ple
_ID
Met
hod
Init
ial
wei
ght
(kg
)G
rain
siz
eP
reco
ncen
trat
eC
onc
entr
ate
d>
3.3
gcm
-3Fi
ne f
ract
ion
in c
onc
entr
ate
(mm
)W
eig
ht (g
)w
t%
init
ial w
eig
htW
eig
ht (g
)w
t%
init
ial w
eig
ht<
0.10
mm
(g)
<0.
10 m
m (w
t%)
3”K
nels
on45
.1<
1 m
m
426/
12-P
OH
D
rive
1_R
ound
131
1.4
0.7
25.2
8.1
8.6
34.1
426/
12-P
OH
D
rive
1_R
ound
235
9.1
0.8
55.1
15.3
9.9
18.0
426/
12-P
OH
D
rive
1_R
ound
332
7.7
0.7
16.6
5.1
6.5
39.2
426/
12-P
OH
D
rive
329
3.8
0.7
6.3
2.2
2.9
45.1
426/
12-P
OH
D
rive
425
2.1
0.6
6.3
2.5
2.8
45.0
426/
12-P
OH
D
rive
531
6.4
0.7
7.7
2.4
3.2
41.6
Tota
l18
60.5
4.1
117.
36.
333
.928
.9
Sha
king
tab
le25
0.9
< 1
mm
426/
12-P
OH
R
ound
118
79.0
0.7
1024
.854
.540
9.1
39.9
426/
12-P
OH
R
ound
218
08.2
0.7
348.
519
.318
9.3
54.3
Tota
l36
87.2
1.5
1373
.337
.259
8.4
43.6
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Geological Survey of Finland, Special Paper 57Marja Lehtonen, Yann Lahaye, Hugh O’Brien, Sari Lukkari, Jukka Marmo and Pertti Sarala
Tabl
e 3.
Min
eral
ogic
al co
mpo
sitio
n of
hea
vy li
quid
sepa
rate
d an
d ce
ntrif
uged
test
till
sam
ples
.
grai
n si
ze 1
00-2
50 µ
m63
-100
µm
-63
µm
den
sity
gcm
-3d
<3.
3d
>3.
3d
<3.
3d
>3.
3d
<3.
3d
>3.
3
wt%
of s
amp
le90
-95.
50.
5-10
95-9
91-
598
-99
1-2
% t
ota
l fea
ture
s%
to
tal f
eatu
res
% t
ota
l fea
ture
s%
to
tal f
eatu
res
% t
ota
l fea
ture
s%
to
tal f
eatu
res
Pla
gioc
lase
22.6
0.5
25.2
0.5
23.6
0.0
K-f
eld
spar
16.7
0.2
16.7
0.3
16.3
0.2
Qua
rtz
45.4
0.8
40.0
1.6
46.2
0.1
Mic
a11
.517
.412
.612
.58.
35.
2
Chl
orite
1.6
2.7
1.9
2.4
2.2
1.5
Am
phi
bol
e1.
010
.31.
18.
71.
013
.8
Pyr
oxen
e0.
00.
80.
01.
00.
12.
9
Gar
net
0.1
13.0
0.5
10.7
0.1
14.8
Ep
idot
e0.
26.
00.
510
.40.
510
.8
Sp
hene
0.1
4.7
0.2
7.1
0.3
9.3
Tour
mal
ine
0.1
0.5
0.2
0.3
0.2
0.1
Zirc
on0.
00.
80.
02.
60.
02.
0
Fe-o
x0.
238
.00.
536
.00.
231
.6
Ilmen
ite0.
03.
50.
03.
80.
05.
0
Ti-O
x0.
00.
50.
01.
30.
01.
5
Ap
atite
0.1
0.2
0.2
0.3
0.3
0.4
Mon
azite
0.0
0.1
0.0
0.3
0.0
0.5
Cal
cite
0.2
0.0
0.3
0.0
0.5
0.0
Sul
phi
des
0.0
0.0
0.0
0.0
0.0
0.1
Gyp
sum
0.0
0.1
0.0
0.1
0.0
0.0
TOTA
L10
0.0
100.
010
0.0
100.
010
0.0
100.
0
Ana
lyze
d g
rain
s8
139
8 25
98
439
10 1
358
450
8 38
6
min
eral
col
our
cod
esd
ensi
ty <
3.3
gcm
-3d
ensi
ty ±
3.3
gcm
-3d
ensi
ty >
3.3
gcm
-3
31
Geological Survey of Finland, Special Paper 57Novel technologies for indicator mineral-based exploration
Fig. 3. a) Heavy mineral concentrate, d >3.3 g·cm-3, grain size <63 μm, non-magnetic fraction. Sample HAH1-2013-1.1 9-10.1m. BSE. Jeol JSM-5900LV. b) Light mineral fraction, d <3.3 g·cm-3, grain size <63 μm. Sample HAH1-2013-1.1 9-10.1m. BSE. Jeol JSM-5900LV.
Fig. 4. A simplified sample processing flowsheet for the NovTecEx samples. The green boxes indicate optional processing steps that were only carried out on a subset of samples.
Preconcentrate Screening 0.063, 0.1, 0.25, 0.5 mm
<0.063, 0.063-‐0.1mm heavy liquid separa�on
d =3.3 gcm-‐3 centrifuge
0.1-‐0.25, 0-‐25-‐0.5, 0.5-‐1.0 mm heavy liquid separa�on
d=3.3 gcm-‐3
funnel
d>3.3 gcm-‐3
-‐0.063 mm magne�c separa�on
d>3.3 gcm-‐3 0.063-‐0.1mm
magne�c separa�on
d>3.3 gcm-‐3 magne�c separa�on
<1.0 mm Shaking table
Wet screening 1.0 mm
Trace element geochemistry SC-‐ICPMS
I Electron op�cal analysis LV-‐SEM Main mineralogy
II Electron op�cal analysis FE-‐SEM Detailed mineralogy
Till sample Drilled (mean 5 l/8 kg)
Excavated (mean 12 l/18 kg)
d<3.3 gcm-‐3
archived d<3.3 gcm-‐3
archived
>1.0mm archived
magne�c frac�on
archived
d>3.3 gcm-‐3
-‐0.063 mm magne�c frac�on
d>3.3 gcm-‐3
-‐0.063 mm non-‐magne�c frac�on
d>3.3 gcm-‐3
0.063-‐0.1 mm non-‐magne�c frac�on
Division into three subsamples
magne�c frac�on
archived
0.1-‐0.25 mm non-‐magne�c
frac�on archived 0.25-‐0.5, 0.5-‐1.0 mm non-‐magne�c frac�on
op�cal microscopy
Subsample 100g
Screening 0.063 mm
<0.063 mm
>0.063 mm archived
32
Geological Survey of Finland, Special Paper 57Marja Lehtonen, Yann Lahaye, Hugh O’Brien, Sari Lukkari, Jukka Marmo and Pertti Sarala
Sample processing at the ODM Laboratory
In order to obtain independent reference data for sample processing, a set of NovTecEx samples was sent to Overburden Drilling Management Ltd in Ottawa (ODM). The samples consisted of ten 12-l original till samples and ten heavy mineral con-centrates of their duplicate samples processed at GTK. The ODM laboratory provides sample-pro-cessing services for indicator mineral work relat-ed, for instance, to gold, diamond and base metal
exploration. The laboratory is routinely used by the Geological Survey of Canada for sample pro-cessing in various types of research projects.
The ODM processing protocol for till samples is quite similar to that used at GTK for this pro-ject (Averill & Huneault 2006). Preconcentration is carried out using a shaking table, followed by heavy liquid and magnetic separations. Gold and PGM grains are separately concentrated by micro-panning.
Analytical methods
LV-SEM-EDS for main mineralogy
The heavy mineral concentrate of the Ilomantsi test sample was studied using an automated SEM attached to an EDS system. The aim was to estab-lish a practical and rapid method to examine the main mineralogy of the NovTecEx samples by an-alysing a few thousand mineral grains from each concentrate. Basic knowledge of the mineralogy was considered important in designing the chemi-cal analysis method for the concentrates, and also in interpreting the results. Finding indicator min-eral grains during this preliminary SEM investiga-tion was not anticipated due to the low number of analysed grains. Detailed mineralogical studies for indicator minerals were only intended to be car-ried out for selected samples based on the chemi-cal analysis results.
Two different types of preparation methods were investigated using the test sample: grain mounts and polished epoxy mounts. The grain mounts were prepared by simply scattering sample material on adhesive carbon discs, meaning they were much faster and cheaper to produce than polished mounts. The disadvantage, however, was that the analysis quality was not as good as from the polished surface. The SEM-EDS results of the test runs are presented in Figure 5, diagrams A-F, both as numbers of analysed mineral grains and as their measured areas. The results indicate that the main mineralogical composition is quite similar, regardless of the sample preparation type. Thus, the grain mounts were considered adequate when focusing on the bulk mineralogy. For detailed mineralogical analysis, polished epoxy mounts were exclusively used.
The SEM-EDS results for the main mineralogy were also compared with conventional chemi-cal analysis by XRF performed in Labtium (code 175X). This was to ensure that the amount of sam-ple used for SEM-EDS analysis was enough to give reliable results. Even though the number of analysed grains can easily reach thousands or tens of thousands, by mass they represent a very small amount of concentrate, usually some tens of mil-ligrams. In contrast, the XRF analysis is performed on a pellet made out of a pulverized sample weigh-ing 7 g at minimum, meaning at least 100 times more material for analysis than with SEM-EDS.
Table 4 presents the mineral composition of the Ilomantsi heavy mineral concentrates deter-mined by SEM-EDS using grain mounts for three grain-size classes. Each result is a combination of three subsamples. The results demonstrate how the mineral compositions vary in relation to grain size. The amounts of amphiboles, epidote, titanite and staurolite clearly decrease as a function of the grain size, whereas the amount of Fe oxides, chro-mite, zircon and monazite increases.
The unclassified mineral class comprises analy-ses that were not identified. In practice, they repre-sent poor quality analytical data resulting from the unpolished grain mounts. The number of unclassi-fied analyses increases in relation to the grain size because the topography of the sample also increas-es. For this reason, grain mounts are best used only for the fine fractions.
When comparing the mineralogy with the XRF analyses, there is a clear correlation between cer-tain minerals and elements. For example, the con-centration of Ca correlates with that of epidote, Ti with ilmenite, Fe with Fe-oxides, Zr with zircon and Ce with monazite. One of the easiest element
33
Geological Survey of Finland, Special Paper 57Novel technologies for indicator mineral-based exploration
0
10
20
30
40
% o
f fea
ture
s H1 PM feat (n=1500)
H1 GM feat (n=1500)
H1 PM area (n=1500)
H1 GM area (n=1500)
0
10
20
30
40
% o
f fea
ture
s
H2 PM feat (n=1500)
H2 GM feat (n=1500)
H2 PM area (n=1500)
H2 GM area (n=1500)
0
10
20
30
40
50
% o
f fea
ture
s
H3 PM feat (n=1500)
H3 GM feat (n=1500)
H3 PM area (n=1500)
H3 GM area (n=1500)
0
10
20
30
40
50
60
% o
f fea
ture
s
K2 PM feat (n=1500)
K2 GM feat (n=1500)
K2 PM area (n=1500)
K2 GM area (n=1500)
0
10
20
30
40
% o
f fea
ture
s
K1 PM feat (n=1500)
K1 GM feat (n=1500)
K1 PM area (n=1500)
K1 GM area (n=1500)
0
10
20
30
40
% o
f fea
ture
s
K3 PM feat (n=1500)
K3 GM feat (n=1500)
K3 PM area (n=1500)
K3 GM area (n=1500)
Fig. 5. Mineral composition of six heavy mineral concentrates (a–f) produced from the Ilomantsi sample. Density >3.3 g·cm-3, grain size <0.1 mm, PM = polished epoxy mount, GM = grain preparate, H = <0.1 mm, K = 0.1–0.25 mm. Data: Jeol JSM-5900LV + Oxford Instruments EDS, INCA Feature software.
a)
c)
e)
b)
d)
f)
concentrations to correlate with the mineral dis-tribution is Zr, since it exclusively exists in zircon in the Ilomantsi sample. When Zr concentrations are calculated based on the SEM mineral composi-tion, the results match quite well with Zr measured
by XRF. The same applies to Ce bound in monazite and Cr bound in chromite and Cr-Fe spinel. The results validate the SEM-EDS method for reliable determination of the main mineralogical compo-sitions of the heavy mineral concentrates.
34
Geological Survey of Finland, Special Paper 57Marja Lehtonen, Yann Lahaye, Hugh O’Brien, Sari Lukkari, Jukka Marmo and Pertti Sarala
Tabl
e 4.
Min
eral
ogic
al (L
V-SE
M-E
DS)
and
chem
ical
(XRF
) com
posit
ion
of th
e Ilo
man
tsi s
ampl
e he
avy
min
eral
conc
entr
ates
. The
XRF
ana
lyse
s wer
e pe
rfor
med
by
Labt
ium
.
TP
R-1
TP
R-1
TP
R-1
TP
R-1
TP
R-1
TP
R-1
Gra
in s
ize
mm
0.1-
0.5
mm
0.06
3-0.
1 m
m<
0.06
3 m
mG
rain
siz
e m
m0.
1-0.
5 m
m0.
063-
0.1
mm
<0.
063
mm
Den
sity
gcm
-3d
>3.
3d
>3.
3d
>3.
3D
ensi
ty g
cm-3
d>
3.3
d>
3.3
d>
3.3
Set
1-3
Set
1-3
Set
1-3
L130
0765
6L1
3005
911
L130
0591
2C
lass
Ave
rag
e d
ensi
tyFe
atur
es%
to
tal
feat
ures
%
mas
sFe
atur
es%
to
tal
feat
ures
%
mas
sFe
atur
es%
to
tal
feat
ures
%
mas
sE
lem
ent
(175
X)
%
%
%
Qua
rtz
2.62
270.
20.
264
0.6
0.4
140.
00.
0E
lem
ent
(175
X)
%
%
%
K-f
sp2.
567
0.1
0.0
60.
10.
01
0.0
0.0
Na2
O0.
251
0.10
30.
079
Alb
ite2.
624
0.0
0.0
180.
20.
10
0.0
0.0
MgO
1.41
00.
630
0.49
2P
lagi
ocla
se2.
656
0.1
0.0
30.
00.
00
0.0
0.0
Al2
O3
12.6
06.
164.
19B
iotit
e3.
4019
0.2
0.2
250.
30.
215
0.1
0.0
SiO
224
.50
12.4
09.
59M
g-b
iotit
e2.
8080
0.7
0.5
290.
30.
221
0.1
0.1
P2O
50.
132
0.14
60.
315
Clin
ochl
ore
2.65
750.
70.
548
0.5
0.3
400.
20.
1K
2O0.
129
0.05
20.
041
Fe-H
ornb
lend
e3.
4794
18.
67.
934
03.
42.
870
52.
92.
2C
aO10
.29
4.30
3.34
Mg-
Hor
nble
nde
3.23
100.
10.
14
0.0
0.0
40.
00.
0Ti
O2
9.60
18.8
020
.11
Act
inol
ite3.
0424
0.2
0.2
60.
10.
012
0.0
0.0
MnO
0.83
1.16
1.02
Cum
min
gton
ite3.
3526
0.2
0.2
160.
20.
18
0.0
0.0
Fe2O
338
.90
52.0
054
.40
Dio
psi
de
3.40
410.
40.
311
0.1
0.1
20.
00.
0S
0.02
00.
035
0.03
2E
pid
ote
3.45
4 02
936
.933
.71
914
19.4
15.8
2 56
510
.78.
0C
l0.
012
0.00
60.
009
Clin
ozoi
site
3.34
158
1.4
1.3
620.
60.
512
0.0
0.0
Sc
0.00
50.
002
0.00
3Ti
tani
te3.
4865
56.
05.
541
14.
23.
454
22.
31.
7V
0.06
10.
080
0.08
5S
chor
l3.
1527
0.2
0.2
170.
20.
129
0.1
0.1
Cr
0.04
90.
093
0.12
5A
pat
ite3.
1915
0.1
0.1
180.
20.
193
0.4
0.3
Ni
0.00
50.
007
0.01
0A
l-si
licat
e3.
610
0.0
0.0
210.
20.
20
0.0
0.0
Cu
0.00
2<
0.00
2<
0.00
2Z
ircon
4.65
730.
70.
837
13.
84.
11
352
5.6
5.7
Zn
0.01
40.
016
0.01
7M
onaz
ite5.
153
0.0
0.0
90.
10.
182
0.3
0.4
Ga
<0.
002
<0.
002
<0.
002
Pyr
ochl
ore
5.30
00.
00.
00
0.0
0.0
10.
00.
0A
s0.
014
0.03
40.
029
Alm
and
ine
4.19
384
3.5
3.9
411
4.2
4.1
514
2.1
1.9
Rb
0.00
30.
005
0.00
6S
pes
sart
ine
4.18
550.
50.
645
0.5
0.5
490.
20.
2S
r0.
088
0.03
20.
024
Sta
urol
ite3.
7162
0.6
0.6
590.
60.
57
0.0
0.0
Y0.
017
0.02
90.
042
Oliv
ine
3.32
40.
00.
00
0.0
0.0
10.
00.
0Z
r0.
565
2.69
53.
991
Hem
atite
5.30
891
8.2
11.5
2 26
122
.928
.78
670
36.1
41.3
Nb
0.00
40.
001
<0.
0007
Goe
thite
3.80
677
6.2
6.2
561
5.7
5.1
713
3.0
2.4
Mo
<0.
001
0.00
90.
017
Ilmen
ite4.
7299
29.
111
.41
812
18.4
20.5
7 12
529
.730
.2S
n0.
005
0.00
60.
005
Fe-T
i ox
5.00
180.
20.
283
0.8
1.0
216
0.9
1.0
Sb
<0.
01<
0.01
<0.
01C
hrom
ite4.
790
0.0
0.0
70.
10.
126
0.1
0.1
Ba
0.02
80.
054
0.05
5C
r-Fe
-sp
inel
5.00
30.
00.
021
0.2
0.3
114
0.5
0.5
La0.
018
0.03
80.
078
Rut
ile_T
i-O
x4.
2563
0.6
0.6
136
1.4
1.4
282
1.2
1.1
Ce
0.04
30.
070
0.15
4G
alen
a7.
400
0.0
0.0
10.
00.
010
0.0
0.1
Pb
0.01
00.
025
0.08
8A
rsen
opyr
ite6.
070
0.0
0.0
20.
00.
00
0.0
0.0
Bi
<0.
003
0.00
30.
006
Sco
rod
ite3.
200
0.0
0.0
30.
00.
00
0.0
0.0
Th0.
015
0.01
60.
026
Gol
d17
.64
00.
00.
00
0.0
0.0
10.
00.
0U
0.00
30.
005
0.00
8U
ncla
ssifi
ed
3.50
1 53
614
.113
.01
064
10.8
8.9
806
3.4
2.5
Tota
l10
905
100.
010
0.0
9 85
910
0.0
100.
024
019
100.
010
0.0
Zr
% (c
alcu
late
d)
0.36
1.78
2.44
Ce
% (c
alcu
late
d)
0.01
0.03
0.11
Cr
% (c
alcu
late
d)
0.01
0.09
0.15
35
Geological Survey of Finland, Special Paper 57Novel technologies for indicator mineral-based exploration
LV-SEM-EDS analytical parameters The analyses were performed using GTK’s Jeol JSM-5900LV scanning electron microscope (SEM), which is attached to an energy dispersive spectrometer (EDS) by Oxford Instruments con-trolled by INCA Feature software. The analytical conditions in the SEM were as follows: low vacuum mode (22 Pa), a COMPO back-scattered signal, 20 kV accelerating voltage and 1 nA probe current. The EDS analyses were carried out on the longest chord of the detected mineral grains with 5 µm as the smallest expected feature width. From each sample preparate, 3000–5000 individual mineral grains were analysed. The mineral identification was based on GTK’s internal mineral database.
Microwave digestion and HR-SC-ICPMS analyses for trace elements
The results in Table 4 demonstrate how low the concentrations of interesting minerals can be in till. For example, only a grain of gold and pyro-chlore was discovered among 20 000 analysed grains in the fine fraction (0.063 mm) heavy min-eral concentrate. In some cases, such as in diamond exploration (e.g. Lehtonen et al. 2005), even 100 times lower concentrations of specific indicator minerals can be crucial when exploring for an ore deposit in an area. Detecting such extreme trace element concentrations in heavy mineral concen-trates requires an ultra-sensitive chemical analysis method. Development was carried out on SGL’s recently installed high-resolution single collector inductively coupled mass spectrometer (HR-SC-ICPMS), which provides the means to analyse trace element concentrations well below the ppb level. The aim was to analyse a subsample of each concentrate by HR-SC-ICPMS, and then use the results to select specific samples to mount for de-tailed mineralogical mapping by FE-SEM-EDS. Prior to HR-SC-ICPMS analysis, the concentrates need to be dissolved, and the development of an efficient and time-saving dissolution method was an important step in the process. The dissolution protocol was built around a microwave digestion technique, using a system that had also been newly installed at SGL.
Microwave digestion is a commonly used meth-od for the mostly partial dissolution of environ-mental samples in many commercial laboratories, including Labtium. The method has not been widely applied in the total dissolution of heavy
mineral concentrates. To obtain background in-formation for the process development at GTK, some Ilomantsi heavy mineral concentrates were sent to Labtium for microwave digestion and sub-sequent ICP-MS analysis (Labtium code 310). Nine 100-mg reference samples were subjected to microwave digestion in a mixture of hydrochloric, nitric and hydrofluoric acid, followed by analysis of the resulting solution by ICP-MS. The analysed material was the same as that measured by XRF for major element compositions (Table 4). As ex-pected, the concentrates did not dissolve entirely in the microwave. The remaining undigested ma-terials were analysed by SEM-EDS for mineralogi-cal composition at GTK.
The Labtium results are presented in Appendix I. When comparing the ICP-MS analyses of the partially digested samples with the corresponding XRF analyses, it can be seen that the concentra-tions of certain elements (Zr, Y, La, Ce, Ba, Cr) are systematically lower in the former. The SEM-EDS analyses of the undigested residual mate-rial confirmed that especially the finest fractions contained abundant chemically resistant miner-als such as zircon, xenotime, monazite, barite and chromite, which are also the main carriers of the elements that gave low results in the ICP-MS data.
The Labtium results demonstrated which min-erals, in particular, are the most difficult ones to dissolve. The resulting dissolution protocol and analytical methods are explained below.
Sample dissolutionSamples (500 mg) were dissolved in Teflon PFA pressure vessels using an Ethos 1 microwave diges-tion system from Milestone Inc. The samples were first dissolved with a mixture of 4 ml HCl 6N and 4 ml HNO3 6.5 N at 220 °C for 45 min. The superna-tant of the first dissolution step was extracted and stored in a separate beaker. The residue of the first dissolution was again attacked using with a mix-ture of 3 ml HCl with 4 ml HNO3 and 2 ml HF at 230 °C for 45 min. The resulting fluoride salts were converted to nitrates by drying down after adding 2 ml of concentrated HNO3. The supernatant of the first dissolution step was mixed with the fully dissolved sample from the second dissolution step. The sample was diluted 5000 times in 250 ml of 2% HNO3 with traces of HF (to stop Zr and Hf pre-cipitation) and spiked with 1 ppb In as the internal standard.
36
Geological Survey of Finland, Special Paper 57Marja Lehtonen, Yann Lahaye, Hugh O’Brien, Sari Lukkari, Jukka Marmo and Pertti Sarala
Method of analysisSamples were analysed using a Nu AttoM HR-SC-ICPMS (Nu Instruments Ltd., Wrexham, UK). The analytical strategy was that developed by Cheatham et al. (1993). This technique uses a matrix-matched external standardization method and non-linear response drift corrections. A series of well-characterized USGS internal standards, BIR-1, BHVO and BCR2, were used. A blank was measured before each sample and standard. The standard BHVO was used to monitor instrument drift and was analysed every 10 positions.
Operating parametersThe normal parameters of operation of the ICP-MS include the use of an autosampler, peristaltic pump and Meinhard nebulizer. Analyses were per-formed in peak jumping mode using 10 sweeps of 50 cycles. A typical element menu consisted of 97 isotopes from 65 elements. Several non-isobaric isotopes of the same elements were used in order to correct for potential interferences. The wash time between samples was 180 s, and a further 60 s of sample uptake was allowed before measurement started. Blank nitric acid aliquots were run before each sample and the resulting values were used to blank-subtract the standard and sample data.
Data reductionThe results were calculated using an in-house Ex-cel data reduction program. After the blank sub-traction and overall drift correction based on the internal standard indium, a polynomial curve was
fitted to the BHVO standard data for each isotope, allowing a specific drift correction for each isotope to be applied. A calibration curve for each isotope forced to the origin and based on three USGS standards was used to calculate concentrations.
FE-SEM-EDS for detailed mineralogical mapping
Selected samples were analysed at GTK using a JEOL JSM 7100F field emission scanning electron microscope attached to an Oxford Instruments EDS. The FE-SEM-EDS system was operated by INCA and Aztec software. The samples for analysis were selected based on the preliminary LV-SEM-EDS mapping for major mineralogy and the HR-SC-ICPMS analyses for trace element concentra-tions. Analyses were performed on polished epoxy mounts made from <63-µm fractions of till. From each mount, approximately 150 000–250 000 indi-vidual mineral grains were automatically scanned, and the BSE signal strength (i.e. mean atomic num-ber) was used to target certain mineral phases for analysis. Elemental distribution mapping was also used for detailed mineralogy. The mineral identifi-cation was based on GTK’s own mineral database.
The analytical conditions in the SEM were as follows: high vacuum mode, a COMPO back-scattered signal, 20 kV accelerating voltage and 1 nA probe current. The EDS spectra were generated from the entire surface areas of the detected min-eral grains, with 2.5 µm as the smallest expected feature width.
RESULTS
ODM optical microscopy results
The optical microscopy results for the grain size fraction of 0.25–1.0 mm are reported in Appendix II. The mineralogy of the ODM- and GTK-pro-cessed samples compared well with each other, in-dicating that the processing systems worked simi-larly. During the micro-panning at ODM, gold and PGM grains were recovered from most of the samples. The number of gold grains varied from 5 to 50 grains per sample, and PGM grains from
0 to 4 (Appendix III). The smallest recovered gold grains were 15 x 15 x 3 µm in size, and the largest 250 x 450 x 150 µm. The combined weights of the gold grains were converted to estimated Au con-tents of the concentrates, which varied between 2–1200 ppb. The detected PGM grains were all un-der 50 µm in diameter and too few to allow PGE concentration calculations.
37
Geological Survey of Finland, Special Paper 57Novel technologies for indicator mineral-based exploration
GTK results: new sample processing and analytical protocol
The NovTecEx preconcentrates weighed 400 g on average (range 100–1000 g) and comprised ap-proximately 5% of the <63 μm fine fraction (range 0.3–21%). The fine fraction had already been con-centrated during tabling, and consequently con-sisted of more than 60% heavy minerals with a density of over 3.3 g·cm-3. Approximately half of this portion was magnetite.
The sample processing and analysis followed the new protocol developed for the project, as follows.
Stage 1: Main mineralogy by LV-SEM-EDS
In total, 68 NovTecEx heavy mineral concentrates were analysed by LV-SEM-EDS for mineralogical composition. Both non-magnetic and magnetic (>0.1 T) fractions were analysed from the grain size fraction <0.063 mm. The results are published in Lehtonen et al. (2014).
The mineralogy of the non-magnetic fractions varies greatly, as expected based on the large and diverse sampling area (Fig. 1). The most abundant heavy minerals include ilmenite, Fe-oxides (most-ly hematite and goethite in non-magnetic frac-tions), titanite, zircon, Fe-hornblende and epidote. Rutile, monazite, almandine, apatite and chromite are also common. The graph in Figure 6 illustrates the compositional variation of the concentrates. In the diagram, the abundances of selected minerals are expressed as numbers of grains per 1000 ana-lysed grains.
The magnetic fractions are dominated by mag-netite and ilmenite (ilmenomagnetite). They also contain approximately 10–20% of mineral grains that should have been separated into the non-magnetic fractions, such as rutile, chromite, zircon and monazite, meaning that the magnetic separa-tion was not entirely accurate.
Observations of indicator minerals are listed in Table 5. The results are combined from both mag-netic and non-magnetic fractions. No gold or PGE grains were detected in the heavy mineral concen-trates during this step of the analysis. This is prob-ably due to the relatively low number of analysed grains (max. 5000) per sample. Based on the mi-cro-panning results of ODM, discovering a gold or PGE grain in this small amount of sample would have been purely accidental.
Despite the relatively low detection limits for minor phases in this step using the LV-SEM, some
contamination was detected. Most commonly, this consisted of chips of stainless steel and cupro-nickel, and sometimes solder. Most probably the contamination occurred during the sampling or preconcentration stages of the process.
Stage 2: Trace element geochemistry by HR-SC-ICPMS
The HR-SC-ICPMS data are presented in Appen-dix IV. As expected, the trace element contents of the samples show broad variation. An interesting set of analyses are labelled as 1–5 (a,b,c). They are reference samples representing different splits of the same starting fine fractions (<0.063 mm) of till. (1) The a samples are unprocessed other than
screening; (2) the b samples are concentrates separated by
heavy liquid; (3) the c samples are tabled and heavy liquid sepa-
rated concentrates.
The main difference between the b and c samples is the size of the original volume of till they are derived from; this is less than 0.5 l for the b sam-ples and from 5 to 12 l for the c samples. The HR-SC-ICPMS data show a clear correlation of certain elements with the sample type, meaning either en-richment of or a decrease in specific minerals as a function of processing. Elements such as REE, Nb, Y, Th, U, Pb, Bi, W, Au and PGE, which are exclu-sively bound to heavy minerals, are concentrated in the c samples. Contrastingly, elements such as Li, Be and Rb follow the opposite trend, as they mostly occur in lighter minerals. Many elements (e.g. Cr, Ni, Cu, Co) do not appear to show any particular discernible patterns.
When the results are studied in the context of the main mineralogy by LV-SEM-EDS (Table 5 and Lehtonen et al. 2014), some matches can be de-tected. Sample RM_HAH1-2013-1.1 (number 17 in Appendix IV), which is the only one containing pentlandite, is clearly enriched in Ni compared to the other concentrates (>5000 ppm). Sample RM_POSS-2012-38.1 (number 7), on the other hand, contains over 1% of chromite, which is reflected by its Cr concentration of over 6000 ppm. Another chromite-rich sample, RM_JOVS-2012-2.1 (16), has more than 5000 ppm of Cr, which is well above the average of the concentrates. The monazite-rich
38
Geological Survey of Finland, Special Paper 57Marja Lehtonen, Yann Lahaye, Hugh O’Brien, Sari Lukkari, Jukka Marmo and Pertti Sarala
0
100
200
300
400
500
600
700
800
900
1000
HAH1 1.1 HAH1 5.1
HAH1 500.1 HAH1 501.1 HAH1 502.3 HAH1 504.1 HAH1 505.1 HAH1 507.1 HAH1 509.1 HAH1 511.1 HAH1 512.1
JOV$ 1.1 JOV$ 2.1 JOV$ 3.1 JOV$ 4.1 JOV$ 9.1
JOV$ 11.2 JOV$ 15.2 JOV$ 21.2 JOV$ 25.2 JOV$ 32.1 POS$ 32.1 POS$ 33.3 POS$ 36.2 POS$ 38.1 POS$ 41.2 POS$ 42.2 POS$ 43.3 POS$ 45.2 POS$ 46.2 POS$ 46.4 POS$ 47.1 POS$ 48.2 POS$ 50.2 POS$ 51.2 POS$ 53.2 POS$ 55.2 POS$ 56.2 POS$ 57.3 POS$ 61.2 POS$ 63.2 POS$ 64.2 POS$ 65.2 POS$ 66.1 POS$ 66.2 POS$ 68.2 POS$ 69.2 POS$ 71.2 POS$ 72.2 POS$ 73.2 POS$ 75.2 POS$ 77.2 POS$ 77.6 POS$ 83.2 POS$ 84.2 POS$ 85.2 POS$ 86.2 POS$ 88.2 POS$ 89.2 POS$ 89.4 POS$ 89.5 POS$ 90.1 POS$ 90.2 POS$ 90.4 POS$ 92.4 POS$ 93.4 POS$ 97.2
POS$ 102.2
Features / 100
0 an
alyzed
grains
Zirc
on
Sphe
ne
Epid
ote
Chlo
rite
Fe
-‐Hor
nble
nde
Fe-‐o
x (g
oeth
ite/l
imon
ite)
Fe-‐o
x (h
ema�
te)
Ilmen
ite
Fig.
6. Th
e m
ain
min
eral
pha
ses o
f the
Nov
TecE
x he
avy
min
eral
con
cent
rate
s. G
rain
size
<0.
063
mm
, non
-mag
netic
frac
tions
. Dat
a: Je
ol JS
M-5
900L
V +
Oxf
ord
Inst
rum
ents
ED
S, IN
CA
Fe
atur
e so
ftwar
e.
39
Geological Survey of Finland, Special Paper 57Novel technologies for indicator mineral-based exploration
Table 5. Indicator minerals detected during mineralogical mapping by LV-SEM-EDS. Data: Jeol JSM-5900LV + Oxford Instru-ments EDS, INCA Feature software.
Sample ID grain size density (gcm-3) indicator minerals
RM_HAH1-2013-1.1 <63 µm >3.3 pentlandite, pyrite, pyrrhotite
RM_HAH1-2013-5.1 <63 µm >3.3 pyrite, pyrrhotite, chalcopyrite
RM_HAH1-2012-500.1 <63 µm >3.3 pyrite
RM_HAH1-2012-502.3 <63 µm >3.3 pyrite
RM_HAH1-2012-504.1 <63 µm >3.3 chalcopyrite, pyrite
RM_HAH1-2012-505.1 <63 µm >3.3 pyrite
RM_HAH1-2012-509.1 <63 µm >3.3 gahnite, Nb-Ta-mineral
RM_JOV$-2012-2.1 <63 µm >3.3 pyrite
RM_JOV$-2012-3.1 <63 µm >3.3 pyrite
RM_JOV$-2012-9.1 <63 µm >3.3 pyrite, pyrrhotite
RM_JOV$-2012-32.1 <63 µm >3.3 pyrite
RM_POS$-2012-33.3 <63 µm >3.3 pyrite
RM_POS$-2012-43.3 <63 µm >3.3 gahnite
RM_POS$-2012-46.4 <63 µm >3.3 gahnite
RM_POS$-2012-47.1 <63 µm >3.3 gahnite, Nb-Ta-mineral
RM_POS$-2012-51.2 <63 µm >3.3 pyrite
RM_POS$-2012-56.2 <63 µm >3.3 gahnite
RM_POS$-2012-66.1 <63 µm >3.3 pyrite
RM_POS$-2012-83.2 <63 µm >3.3 pyrite
RM_POS$-2012-85.2 <63 µm >3.3 Ni-mineral (awaruite?)
(1–5%) samples are also easy to identify based on their REE concentrations, with La and Ce exceed-ing the limits of calibration.
However, the LV-SEM-EDS results do not ex-plain the mineralogy behind the most interesting observations. A few specific samples stand out from the bulk with unusual elemental concentra-tions, such as RM_POSS-2012-44.2 and 47.2 (1c and 2c), with over 2000 ppm of Y, 200 ppm of Bi, 100 ppm of W and 5 ppm of Au. Sample RM_POSS-2012-43.3 (10) also has over 2000 ppm of Y, which is also well above the average.
When the HR-SC-ICPMS data are compared with the calculated concentrations of Au by ODM based on the visually observed gold grains, the HR-SC-ICPMS analyses nearly always show sys-tematically higher levels of Au. This is probably due to the limitations in the visual identification of gold. The grains below 15–20 µm in diam-eter cannot be identified, meaning that the finer-grained gold is excluded from the calculations. On the other hand, the calculated Au concentra-tion of sample RM_POS$-2012-41.1 is extremely high, 1200 ppb, compared to the 140 ppb meas-
ured by HR-SC-ICPMS from its reference sample RM_POS$-2012-41.2 (9). The calculated concen-tration, however, is in practice entirely based on one single larger gold nugget with dimensions 120 x 250 x 450 µm (Appendix III). Thus, the seeming discrepancy in the results can be explained in this case by an obvious nugget effect.
Stage 3: Detailed mineralogy by FE-SEM-EDS
Detailed mineralogical investigations were car-ried out by FE-SEM-EDS on selected samples that had been analysed by HR-SC-ICPMS for trace elements. Figures 7a and 7b present mineralogi-cal maps created by INCA MinLib software for the heavy mineral concentrates. The figures dem-onstrate that the material in the <63 µm fraction mostly consists of individual mineral grains with some bimineralic grains and rock fragments. Min-eral inclusions and alteration products can also be detected.
Trace mineral searches were conducted for min-eral phases with a BSE grey-scale at the level of or higher than that of monazite, i.e. a setting to ignore
40
Geological Survey of Finland, Special Paper 57Marja Lehtonen, Yann Lahaye, Hugh O’Brien, Sari Lukkari, Jukka Marmo and Pertti Sarala
Fig. 7. Mineral distribution maps (a–b) over a heavy mineral concentrate. Sample RM_POS$-2012-82.1. Grain size <0.063 mm. Jeol TM JSM-7100F. Oxford Instruments INCAMineral.
41
Geological Survey of Finland, Special Paper 57Novel technologies for indicator mineral-based exploration
all but the densest portion of the heavy mineral concentrates. The aim was to detect gold and PGM that had already been recovered at ODM, and also to find mineralogical explanations for Y-, Bi- and W-rich concentrates.
The results are presented in Table 6. The amount of heavies varies greatly in the concentrates, from 0.1% to over 13% by area. The dominant heavy mineral is monazite, making up 70% to 99% of analysed grains, and representing up to 6% of all scanned mineral grains. The next most common mineral is xenotime, with maximum concentra-tions of 27% of heavies and 0.6% of all scanned minerals. Other heavy minerals, such as pyro-chlore, scheelite, gold, and Pt and Bi minerals, are extremely rare.
The mineralogy of the variably processed refer-ence till samples (1–5, as in Appendix IV) demon-strates that the tabled and separated concentrates (type c) have a systematically higher and more ver-satile content of heavy minerals than their merely HMS-separated counterparts (type b). This ob-servation correlates well with the HR-SC-ICPMS analyses.
The trace element data are also supported by other mineralogical findings. Scheelite and Bi
minerals (mostly Bi oxides) are most commonly found in samples with elevated levels of W and Bi (GK_POS$-2012-44.1 and RM_POS$-2012-44.2) and xenotime in Y-rich samples (e.g. RM_POS$-2012-44.2). The extremely rare findings of gold also coincide with the most Au-rich samples (e.g. RM_POS$-2012-44.2). The largest detected gold grains are 20–30 µm in diameter, but most are micron to sub-micron scale (Fig. 8). The smallest detected gold particles exist as inclusions in other mineral grains, mostly goethite. Within the larger grains, some compositional variation can be de-tected by element distribution mapping, as seen in Figure 9, where a ~200 nm vein of pure gold cuts across a silver-bearing gold grain.
Pt minerals were only detected as inclusions in other minerals, except for one individual grain of sperrylite in sample RM_POS$-2012-97.2 (Fig. 8). The inclusions are submicron scale and too small for reliable mineral identifications. Importantly, the rare Pt-mineral findings match with the elevat-ed Pt concentrations measured by HR-SC-ICPMS, such as in samples RM_POS$-2012-36.2 (900 ppb) and RM_POS$-2012-43.3 (600 ppb).
42
Geological Survey of Finland, Special Paper 57Marja Lehtonen, Yann Lahaye, Hugh O’Brien, Sari Lukkari, Jukka Marmo and Pertti Sarala
GK
_PO
S$-
2012
-44.
11b
RM
_PO
S$-
2012
-44.
21c
Cla
ssFe
atur
es%
ana
lyze
d
feat
ures
% t
ota
l fe
atur
es
(est
.)
Feat
ure
area
(s
q. µ
m)
% a
naly
zed
fe
atur
es a
rea
%
tota
l ar
eaFe
atur
es%
ana
lyze
d
feat
ures
% t
ota
l fe
atur
es
(est
.)
Feat
ure
area
(s
q. µ
m)
% a
naly
zed
fe
atur
es
area
%
tota
l ar
eaM
onaz
ite5
313
97.3
32.
661.
30E
+6
99.2
80.
4613
139
89.8
55.
716.
34E
+6
97.4
31.
57X
enot
ime
122
2.23
0.06
3.60
E+
30.
270.
001
369
9.36
0.60
1.41
E+
52.
170.
03S
chee
lite
100.
180.
013.
25E
+3
0.25
0.00
130.
090.
014.
66E
+3
0.07
0.00
Bi-
min
eral
80.
150.
001.
38E
+3
0.11
0.00
320.
220.
011.
44E
+4
0.22
0.00
Gol
d1
0.02
0.00
2.28
E+
10.
000.
003
0.02
0.00
2.95
E+
20.
000.
00P
yroc
hlor
e2
0.04
0.00
8.06
E+
20.
060.
0049
0.34
0.02
5.55
E+
30.
090.
00N
b-T
a-m
iner
al1
0.02
0.00
1.23
E+
20.
010.
0014
0.10
0.01
3.52
E+
20.
010.
00Th
-min
eral
10.
020.
002.
12E
+2
0.02
0.00
20.
010.
001.
09E
+3
0.02
0.00
Gal
ena
10.
020.
004.
64E
+1
0.00
0.00
10.
010.
004.
92E
+0
0.00
0.00
Pb
-oxi
de
Pt-
min
eral
U-m
iner
al2
0.01
0.00
5.27
E+
00.
000.
00To
tal
5 45
910
0.00
2.73
1.31
E+
610
0.00
0.47
14 6
2410
0.00
6.36
6.51
E+
610
0.00
1.61
Tota
l fea
ture
s (e
stim
ate)
200
000
230
000
Tota
l sca
nned
are
a
(sq
. µm
)2.
81E
+8
4.04
E+
8
SC
-IC
PM
S d
ata
Y p
pm
1 19
02
332
Bi p
pm
6221
1W
pp
m24
526
1N
b p
pm
558
652
Au
pp
b
1 89
55
015
Pt
pp
b15
638
8
OD
M r
esul
ts
Gol
d (g
rain
s)
no d
ata
no d
ata
Pt
(gra
ins)
Sp
erry
lite
(gra
ins)
Au
pp
b c
alcu
late
d
Tabl
e 6.
Res
ults
of h
eavy
min
eral
map
ping
by
FE-S
EM-E
DS.
Jeol
TM
JSM
-710
0F. I
NC
A F
eatu
re. S
C-I
CPM
S da
ta (A
ppen
dix
IV),
OD
M re
sults
(App
endi
x II
I).
43
Geological Survey of Finland, Special Paper 57Novel technologies for indicator mineral-based exploration
GK
_PO
S$-
2012
-47.
22b
RM
_PO
S$-
2012
-47.
22c
Cla
ssFe
atur
es%
an
alyz
ed
feat
ures
% t
ota
l fe
atur
es
(est
.)
Feat
ure
area
(s
q. µ
m)
% a
naly
zed
fe
atur
es a
rea
%
tota
l ar
ea
Feat
ures
%
anal
yzed
fe
atur
es
% t
ota
l fe
atur
es
(est
.)
Feat
ure
area
(s
q. µ
m)
% a
naly
zed
fe
atur
es a
rea
%
tota
l ar
ea
Mon
azite
7 02
187
.07
3.51
2.29
E+
692
.45
0.80
4 67
493
.52
3.90
3.31
E+
695
.33
1.53
Xen
otim
e1
034
12.8
20.
521.
85E
+5
7.47
0.06
313
6.26
0.26
1.57
E+
54.
520.
07S
chee
lite
Bi-
min
eral
50.
060.
001.
37E
+3
0.06
0.00
80.
160.
014.
10E
+3
0.12
0.00
Gol
dP
yroc
hlor
e1
0.02
0.00
4.12
E+
20.
010.
00N
b-T
a-m
iner
alTh
-min
eral
20.
020.
003.
35E
+2
0.01
0.00
Gal
ena
10.
010.
001.
69E
+1
0.00
0.00
Pb
-oxi
de
10.
010.
002.
32E
+2
0.01
0.00
10.
020.
001.
13E
+2
0.00
0.00
Pt-
min
eral
U-m
iner
al1
0.02
0.00
4.12
E+
20.
010.
00To
tal
8 06
410
0.00
4.03
2.48
E+
610
0.00
0.86
4 99
810
0.00
4.17
3.47
E+
610
0.00
1.60
Tota
l fea
ture
s (e
stim
ate)
200
000
120
000
Tota
l sca
nned
are
a
(sq
. µm
)2.
88E
+8
2.17
E+
8
SC
-IC
PM
S d
ata
Y p
pm
734
2 07
4B
i pp
m59
224
W p
pm
6710
7N
b p
pm
468
650
Au
pp
b
108
237
Pt
pp
b86
268
OD
M r
esul
ts
Gol
d (g
rain
s)
Pt
(gra
ins)
Sp
erry
lite
(gra
ins)
Au
pp
b c
alcu
late
d
Tabl
e 6.
Con
t.
44
Geological Survey of Finland, Special Paper 57Marja Lehtonen, Yann Lahaye, Hugh O’Brien, Sari Lukkari, Jukka Marmo and Pertti Sarala
GK
_PO
S$-
2012
-82.
13b
RM
_PO
S$-
2012
-82.
13c
Cla
ss
Feat
ures
%
anal
yzed
fe
atur
es
% t
ota
l fe
atur
es
(est
.)
Feat
ure
area
(s
q. µ
m)
% a
naly
zed
fe
atur
es
area
% t
ota
l ar
eaFe
atur
es
%
anal
yzed
fe
atur
es
% t
ota
l fe
atur
es
(est
.)
Feat
ure
area
(s
q. µ
m)
% a
naly
zed
fe
atur
es
area
%
tota
l ar
eaM
onaz
ite36
978
.68
0.18
9.64
E+
492
.24
0.03
795
88.5
30.
505.
60E
+5
94.2
70.
20X
enot
ime
100
21.3
20.
058.
11E
+3
7.76
0.00
100
11.1
40.
063.
29E
+4
5.54
0.01
Sch
eelit
eB
i-m
iner
alG
old
Pyr
ochl
ore
20.
220.
001.
11E
+3
0.19
0.00
Nb
-Ta-
min
eral
Th-m
iner
al1
0.11
0.00
1.12
E+
10.
000.
00G
alen
aP
b-o
xid
eP
t-m
iner
alU
-min
eral
Tota
l46
910
0.00
0.23
1.05
E+
510
0.00
0.04
898
100.
000.
565.
94E
+5
100.
000.
21
Tota
l fea
ture
s (e
stim
ate)
200
000
160
000
Tota
l sca
nned
are
a
(sq
. µm
)2.
83E
+8
2.79
E+
8
SC
-IC
PM
S d
ata
Y p
pm
310
289
Bi p
pm
21
W p
pm
1311
Nb
pp
m25
626
5A
u p
pb
50
73P
t p
pb
2714
3
OD
M r
esul
ts
Gol
d (g
rain
s)22
Pt
(gra
ins)
Sp
erry
lite
(gra
ins)
Au
pp
b c
alcu
late
d48
Tabl
e 6.
Con
t.
45
Geological Survey of Finland, Special Paper 57Novel technologies for indicator mineral-based exploration
GK
_PO
S$-
2012
-83.
44b
RM
_PO
S$-
2012
-83.
2 4c
Cla
ssFe
atur
es%
an
alyz
ed
feat
ures
% t
ota
l fe
atur
es
(est
.)
Feat
ure
area
(s
q. µ
m)
% a
naly
zed
fe
atur
es
area
% t
ota
l ar
eaFe
atur
es%
an
alyz
ed
feat
ures
% t
ota
l fe
atur
es
(est
.)
Feat
ure
area
(s
q. µ
m)
% a
naly
zed
fe
atur
es
area
%
tota
l ar
ea
Mon
azite
700
88.8
30.
351.
98E
+5
93.4
90.
071
137
95.3
10.
761.
26E
+6
97.0
50.
47X
enot
ime
789.
900.
041.
11E
+4
5.24
0.00
534.
440.
043.
36E
+4
2.59
0.01
Sch
eelit
eB
i-m
iner
alG
old
Pyr
ochl
ore
20.
250.
008.
71E
+1
0.04
0.00
20.
170.
003.
77E
+3
0.29
0.00
Nb
-Ta-
min
eral
Th-m
iner
al4
0.51
0.00
2.46
E+
31.
160.
00G
alen
aP
b-o
xid
e4
0.51
0.00
1.29
E+
20.
060.
00P
t-m
iner
alU
-min
eral
10.
080.
009.
77E
+2
0.08
0.00
Tota
l78
810
0.00
0.39
2.12
E+
510
0.00
0.08
1 19
310
0.00
0.80
1.30
E+
610
0.00
0.48
Tota
l fea
ture
s (e
stim
ate)
200
000
150
000
Tota
l sca
nned
are
a
(sq
. µm
)2.
82E
+8
2.69
E+
8
SC
-IC
PM
S d
ata
Y p
pm
368
607
Bi p
pm
21
W p
pm
1617
Nb
pp
m41
131
7A
u p
pb
35
113
6P
t p
pb
5824
3
OD
M r
esul
ts
Gol
d (g
rain
s)
Pt
(gra
ins)
Sp
erry
lite
(gra
ins)
Au
pp
b c
alcu
late
d
Tabl
e 6.
Con
t.
46
Geological Survey of Finland, Special Paper 57Marja Lehtonen, Yann Lahaye, Hugh O’Brien, Sari Lukkari, Jukka Marmo and Pertti Sarala
GK
_PO
S$-
2012
-97.
35b
RM
_PO
S$-
2012
-97.
25c
Cla
ssFe
atur
es%
an
alyz
ed
feat
ures
% t
ota
l fe
atur
es
(est
.)
Feat
ure
area
(s
q. µ
m)
% a
naly
zed
fe
atur
es
area
%
tota
l ar
ea
Feat
ures
%
anal
yzed
fe
atur
es
% t
ota
l fe
atur
es
(est
.)
Feat
ure
area
(s
q. µ
m)
% a
naly
zed
fe
atur
es
area
%
tota
l ar
ea
Mon
azite
586
83.4
80.
291.
39E
+5
89.2
60.
051
027
70.9
70.
412.
68E
+5
91.2
80.
06X
enot
ime
110
15.6
70.
061.
44E
+4
9.25
0.01
401
27.7
10.
162.
31E
+4
7.87
0.01
Sch
eelit
eB
i-m
iner
alG
old
40
0.00
6.67
E+
00.
000.
00P
yroc
hlor
e5
00.
008.
01E
+2
0.27
0.00
Nb
-Ta-
min
eral
10.
140.
005.
88E
+2
0.38
0.00
10
0.00
6.79
E+
20.
230.
00Th
-min
eral
50.
710.
001.
74E
+3
1.12
0.00
50
0.00
9.88
E+
20.
340.
00G
alen
a1
00.
004.
22E
+0
0.00
0.00
Pb
-oxi
de
20
0.00
1.55
E+
10.
010.
00P
t-m
iner
al1
00.
002.
46E
+0
0.00
0.00
U-m
iner
alTo
tal
702
100.
000.
351.
56E
+5
100.
000.
061
447
100.
000.
582.
94E
+5
100.
000.
07
Tota
l fea
ture
s (e
stim
ate)
200
000
250
000
Tota
l sca
nned
are
a
(sq
. µm
)2.
77E
+8
4.48
E+
8
SC
-IC
PM
S d
ata
Y p
pm
334
222
Bi p
pm
11
W p
pm
1710
Nb
pp
m30
615
6A
u p
pb
65
50P
t p
pb
3663
OD
M r
esul
ts
Gol
d (g
rain
s)49
Pt
(gra
ins)
Sp
erry
lite
(gra
ins)
1A
u p
pb
cal
cula
ted
43
Tabl
e 6.
Con
t.
47
Geological Survey of Finland, Special Paper 57Novel technologies for indicator mineral-based exploration
RM
_PO
S$-
2012
-36.
26
RM
_PO
S$-
2012
-39.
18
Cla
ssFe
atur
es%
an
alyz
ed
feat
ures
% t
ota
l fe
atur
es
(est
.)
Feat
ure
area
(s
q. µ
m)
% a
naly
zed
fe
atur
es
area
% t
ota
l ar
eaFe
atur
es%
an
alyz
ed
feat
ures
% t
ota
l fe
atur
es
(est
.)
Feat
ure
area
(s
q. µ
m)
% a
naly
zed
fe
atur
es
area
%
tota
l ar
ea
Mon
azite
2 99
183
.13
1.20
2.95
E+
695
.13
0.67
3 29
093
.04
1.57
2.20
E+
695
.62
0.59
Xen
otim
e52
914
.70
0.21
1.47
E+
54.
740.
0323
46.
620.
119.
57E
+4
4.16
0.03
Sch
eelit
eB
i-m
iner
al1
0.03
0.00
4.22
E+
00.
000.
00G
old
40.
110.
009.
84E
+0
0.00
0.00
Pyr
ochl
ore
391.
080.
022.
40E
+3
0.08
0.00
60.
170.
001.
58E
+3
0.07
0.00
Nb
-Ta-
min
eral
20.
060.
001.
42E
+3
0.06
0.00
Th-m
iner
al8
0.22
0.00
1.56
E+
30.
050.
001
0.03
0.00
2.15
E+
30.
090.
00G
alen
a4
0.11
0.00
1.55
E+
10.
000.
001
0.03
0.00
1.26
E+
10.
000.
00P
b-o
xid
e16
0.44
0.01
9.87
E+
10.
000.
002
0.06
0.00
2.53
E+
10.
000.
00P
t-m
iner
al4
0.11
0.00
1.23
E+
10.
000.
00U
-min
eral
20.
060.
004.
92E
+0
0.00
0.00
Tota
l3
598
100.
001.
443.
10E
+6
100.
000.
713
536
100.
001.
682.
30E
+6
100.
000.
61
Tota
l fea
ture
s (e
stim
ate)
250
000
210
000
Tota
l sca
nned
are
a
(sq
. µm
)4.
38E
+8
3.75
E+
8
SC
-IC
PM
S d
ata
Y p
pm
277
525
Bi p
pm
22
W p
pm
129
Nb
pp
m28
427
2A
u p
pb
12
710
1P
t p
pb
902
574
OD
M r
esul
ts
Gol
d (g
rain
s)18
5
Pt
(gra
ins)
11
Sp
erry
lite
(gra
ins)
3A
u p
pb
cal
cula
ted
133
2
Tabl
e 6.
Con
t.
48
Geological Survey of Finland, Special Paper 57Marja Lehtonen, Yann Lahaye, Hugh O’Brien, Sari Lukkari, Jukka Marmo and Pertti Sarala
RM
_PO
S$-
2012
-41.
29
RM
_PO
S$-
2012
-43.
310
Cla
ssFe
atur
es%
an
alyz
ed
feat
ures
% t
ota
l fe
atur
es
(est
.)
Feat
ure
area
(s
q. µ
m)
% a
naly
zed
fe
atur
es
area
%
tota
l ar
ea
Feat
ures
%
anal
yzed
fe
atur
es
% t
ota
l fe
atur
es
(est
.)
Feat
ure
area
(s
q. µ
m)
% a
naly
zed
fe
atur
es
area
%
tota
l ar
ea
Mon
azite
4 13
186
.53
1.65
4.25
E+
694
.85
0.95
21 1
4299
.63
8.81
9.38
E+
610
0.00
2.26
Xen
otim
e62
713
.13
0.25
2.22
E+
54.
950.
0564
0.30
0.03
1.57
E+
20.
000.
00S
chee
lite
10.
000.
007.
38E
+0
0.00
0.00
Bi-
min
eral
20.
040.
009.
78E
+2
0.02
0.00
20.
010.
009.
48E
+0
0.00
0.00
Gol
d1
0.00
0.00
1.76
E+
00.
000.
00P
yroc
hlor
e5
0.10
0.00
3.79
E+
30.
080.
00N
b-T
a-m
iner
al2
0.04
0.00
2.70
E+
30.
060.
00Th
-min
eral
40.
080.
003.
68E
+2
0.01
0.00
20.
010.
009.
48E
+0
0.00
0.00
Gal
ena
10.
000.
003.
16E
+0
0.00
0.00
Pb
-oxi
de
10.
020.
001.
83E
+1
0.00
0.00
70.
030.
004.
57E
+1
0.00
0.00
Pt-
min
eral
10.
000.
001.
76E
+0
0.00
0.00
U-m
iner
al2
0.04
0.00
8.97
E+
20.
020.
00To
tal
4 77
410
0.00
1.91
4.48
E+
610
0.00
1.00
21 2
2110
0.00
8.84
9.38
E+
610
0.00
2.26
Tota
l fea
ture
s (e
stim
ate)
250
000
240
000
Tota
l sca
nned
are
a
(sq
. µm
)4.
48E
+8
4.15
E+
8
SC
-IC
PM
S d
ata
Y p
pm
999
2 15
2B
i pp
m64
5W
pp
m21
58N
b p
pm
357
416
Au
pp
b
140
146
Pt
pp
b62
960
8
OD
M r
esul
ts
Gol
d (g
rain
s)9
13
Pt
(gra
ins)
Sp
erry
lite
(gra
ins)
2A
u p
pb
cal
cula
ted
1200
40
Tabl
e 6.
Con
t.
49
Geological Survey of Finland, Special Paper 57Novel technologies for indicator mineral-based exploration
RM
_PO
S$-
2012
-48.
211
RM
_PO
S$-
2012
-55.
212
Cla
ssFe
atur
es%
an
alyz
ed
feat
ures
% t
ota
l fe
atur
es
(est
.)
Feat
ure
area
(s
q. µ
m)
% a
naly
zed
fe
atur
es
area
%
tota
l ar
ea
Feat
ures
%
anal
yzed
fe
atur
es
% t
ota
l fe
atur
es
(est
.)
Feat
ure
area
(s
q. µ
m)
% a
naly
zed
fe
atur
es
area
%
tota
l ar
ea
Mon
azite
2 55
095
.26
1.02
1.95
E+
699
.30
0.44
1 13
487
.30
0.52
1.27
E+
697
.17
0.32
Xen
otim
e10
63.
960.
043.
64E
+3
0.19
0.00
145
11.1
60.
073.
16E
+4
2.42
0.01
Sch
eelit
eB
i-m
iner
al2
0.07
0.00
8.98
E+
20.
050.
001
0.08
0.00
4.88
E+
10.
000.
00G
old
Pyr
ochl
ore
70.
260.
002.
59E
+3
0.13
0.00
10.
080.
009.
84E
+2
0.08
0.00
Nb
-Ta-
min
eral
30.
110.
002.
68E
+2
0.01
0.00
Th-m
iner
al3
0.11
0.00
4.44
E+
30.
230.
008
0.62
0.00
3.13
E+
30.
240.
00G
alen
aP
b-o
xid
e4
0.15
0.00
5.60
E+
20.
030.
009
0.69
0.00
1.84
E+
20.
010.
00P
t-m
iner
alU
-min
eral
20.
070.
001.
44E
+3
0.07
0.00
10.
080.
009.
84E
+2
0.08
0.00
Tota
l2
677
100.
001.
071.
96E
+6
100.
000.
441
299
100.
000.
591.
31E
+6
100.
000.
33
Tota
l fea
ture
s (e
stim
ate)
250
000
220
000
Tota
l sca
nned
are
a
(sq
. µm
)4.
45E
+8
3.92
E+
8
SC
-IC
PM
S d
ata
Y p
pm
602
498
Bi p
pm
32
W p
pm
1915
Nb
pp
m36
633
7A
u p
pb
12
212
6P
t p
pb
469
434
OD
M r
esul
ts
Gol
d (g
rain
s)23
9
Pt
(gra
ins)
Sp
erry
lite
(gra
ins)
2A
u p
pb
cal
cula
ted
3530
Tabl
e 6.
Con
t.
50
Geological Survey of Finland, Special Paper 57Marja Lehtonen, Yann Lahaye, Hugh O’Brien, Sari Lukkari, Jukka Marmo and Pertti Sarala
RM
_PO
S$-
2012
-66.
113
RM
_PO
S$-
2012
-77.
214
Cla
ssFe
atur
es%
an
alyz
ed
feat
ures
% t
ota
l fe
atur
es
(est
.)
Feat
ure
area
(s
q. µ
m)
% a
naly
zed
fe
atur
es
area
%
tota
l ar
ea
Feat
ures
%
anal
yzed
fe
atur
es
% t
ota
l fe
atur
es
(est
.)
Feat
ure
area
(s
q. µ
m)
% a
naly
zed
fe
atur
es
area
%
tota
l ar
ea
Mon
azite
2 88
498
.94
0.93
6.40
E+
599
.82
0.11
1 66
480
.58
0.67
1.58
E+
696
.37
0.35
Xen
otim
e25
0.86
0.01
7.81
E+
20.
120.
0039
319
.03
0.16
5.40
E+
43.
290.
01S
chee
lite
20.
070.
008.
75E
+1
0.01
0.00
Bi-
min
eral
Gol
dP
yroc
hlor
e1
0.03
0.00
4.46
E+
10.
010.
003
0.15
0.00
3.33
E+
30.
200.
00N
b-T
a-m
iner
al1
0.03
0.00
4.29
E+
10.
010.
001
0.05
0.00
4.35
E+
20.
030.
00Th
-min
eral
20.
070.
001.
88E
+2
0.03
0.00
20.
100.
001.
20E
+3
0.07
0.00
Gal
ena
Pb
-oxi
de
10.
050.
001.
72E
+1
0.00
0.00
Pt-
min
eral
U-m
iner
al1
0.05
0.00
5.21
E+
20.
030.
00To
tal
2 91
510
0.00
0.94
6.41
E+
510
0.00
0.11
2 06
510
0.00
0.83
1.64
E+
610
0.00
0.37
Tota
l fea
ture
s (e
stim
ate)
310
000
250
000
Tota
l sca
nned
are
a
(sq
. µm
)5.
58E
+8
4.48
E+
8
SC
-IC
PM
S d
ata
Y p
pm
439
440
Bi p
pm
21
W p
pm
1013
Nb
pp
m21
037
6A
u p
pb
15
312
2P
t p
pb
463
276
OD
M r
esul
ts
Gol
d (g
rain
s)20
14
Pt
(gra
ins)
Sp
erry
lite
(gra
ins)
1A
u p
pb
cal
cula
ted
7419
Tabl
e 6.
Con
t.
51
Geological Survey of Finland, Special Paper 57Novel technologies for indicator mineral-based exploration
Fig. 8. Gold and sperrylite grains detected in the NovTecEx heavy mineral concentrates. a–b) gold grains in sample RM_POS$-2012-44.2 c–d) gold as inclusions in goethite in sample RM_POS$-36.2 e) submicron-scale gold particle in sample RM_POS$-2012-43.3, and f) sperrylite grain in sample RM_POS$-97.2. BSE images. Jeol TM JSM-7100F.
52
Geological Survey of Finland, Special Paper 57Marja Lehtonen, Yann Lahaye, Hugh O’Brien, Sari Lukkari, Jukka Marmo and Pertti Sarala
Fig. 9. BSE image (a) of a silver-bearing gold grain in sample RM_POS$-2012-44.1 showing a lighter-coloured vein that is composed of pure gold (b, c). Jeol TM JSM-7100F. AZtec.
53
Geological Survey of Finland, Special Paper 57Novel technologies for indicator mineral-based exploration
DISCUSSION
As ore deposits become increasingly difficult to discover, traditional methods of exploration need to be enhanced through the addition of modern technologies. In this project, conventional sample processing protocols were tuned to meet the needs of modern analytical research instruments. The results demonstrate that, for example, panning combined with optical microscopy is probably still the most efficient method for recovering gold and PGM grains over 10 to 20 µm in size from till. However, a significant proportion of these miner-als exist in even finer grain sizes and, importantly, as inclusions in other mineral grains, which cannot be detected without scanning electron microsco-py. In addition, a considerable variety of indicator minerals (Table 1) cannot be concentrated as effec-tively as gold and PGM and also exist as silt-sized grains, or are otherwise difficult to recognize un-der the optical microscope. A modern automated SEM provides a means to efficiently identify and analyse these types of grains. However, a reliable screening method is needed to select the samples for detailed SEM work.
The conventional elemental analysis of the till matrix is performed on the unprocessed fine frac-tion (<63 µm), which is dominated by quartz, feld-spars and other light “bulk” minerals. These min-erals exist in such high concentrations that they prevent ultra-low concentration (ppb level and beyond) indicator minerals from being detected by chemical analysis. Following the conventional method, the samples are digested prior to analy-sis using aqua regia (3:1 mixture of concentrated hydrochloric acid and concentrated nitric acid), which produces only partial dissolution for many elements. When these two factors are combined, it is clear that conventional till geochemistry cannot be used as a screening method for detailed indica-tor work.
In this project, the heavy mineral concentrates were fully digested by a microwave system and subsequently analysed by HR-SC-ICPMS to detect interesting trace element concentrations, and ul-timately screen the samples for detailed FE-SEM-EDS work. The sample size for digestion was 500 mg, which represented on average 20–25% of the
NovTecEx fine fraction heavy mineral concen-trates after magnetite had been removed. Based on the results, the digested sample size appears to have been adequate for the trace element work. Moreover, since only some tens of milligrams of material are needed for the SEM studies, even smaller original samples might have produced enough fine-fraction heavy minerals for analysis.
The possibility to use a small original sample size is particularly important in projects where the till samples are collected by drilling, and obtaining a larger sample would require a substantial amount of effort. The methodology is also useful when re-analysing previously collected exploration samples for novel purposes when only a restricted amount of pristine sample material is available. In particu-lar, a smaller original sample size is significant re-garding the overall context of the project, where all the actions have aimed at minimizing the use of energy, labour and time spent on sampling, sam-ple processing and analysis, and ultimately on the impact of the exploration activities on the environ-ment.
One of the major challenges in this development project was the delay in the installation of the HR-SC-ICPMS and FE-SEM-EDS laboratories. When the project started in 2012, the new analytical fa-cilities were due to be delivered by the end of the year. In practice, they were finally delivered over a year behind the original schedule, during late No-vember in 2013. The delay meant that not all of the designed experiments could be carried out dur-ing the time frame of the project. These planned aspects included more detailed geochemical and mineralogical investigations on sample material at different stages of processing, and also experi-ments on the effect of using variable grain sizes of the concentrates to achieve statistically meaning ful results. The objective would have been to op-timize the original sample size and detect possible short cuts in the processing line for certain target minerals and metals. Importantly, the methodol-ogy for these tests has now been established and abundant sample material collected during the NovTecEx project also remains available for pos-sible future work.
54
Geological Survey of Finland, Special Paper 57Marja Lehtonen, Yann Lahaye, Hugh O’Brien, Sari Lukkari, Jukka Marmo and Pertti Sarala
CONCLUSIONS
The sample processing protocol designed for the NovTecEx samples turned out to be effective. It was based on a combination of traditional and mod-ern methodologies. Fine-grained heavy minerals were reliably recovered from till, and their over-all mineralogy could be rapidly determined from grain mounts using automated LV-SEM-EDS. As a result, a new dataset was formed on the heavy mineral distribution in till over the Savukoski-Pelkosenniemi sampling area. The most demand-ing aspect of the project was the development of a methodology to completely digest the heavy mineral concentrates for trace element analysis by HR-SC-ICPMS. The resulting protocol is based on microwave digestion and it is far less time-con-suming and laborious than conventional dissolu-tion methods. The analytical capability of HR-SC-ICPMS enables the trace element concentrations to be measured below 1 ppb levels. The detailed mineralogical investigations by FE-SEM-EDS re-
vealed that even submicron-scale indicator min-eral grains could be detected either as individual grains or as inclusions in other minerals.
The results of this project demonstrate that the use of modern research instruments can signifi-cantly reduce the sample size needed for exploring mineralizations in an area. In this study, the aver-age sample size was relatively small (5 l) to begin with, but in most cases processing even half of that would probably have been enough. A smaller sam-ple size obviously means less effort during sam-pling and sample processing, and above all, less impact on the environment. Further tests should still be carried out to determine the optimal sam-ple size for different types of investigations, and also more experiments to detect possible shortcuts in the sample processing protocol. The remaining unprocessed NovTecEx samples provide good test material for future development.
ACKNOWLEDGEMENTS
Beth McClenaghan and Isabelle McMartin from the Geological Survey of Canada are thanked for collaborating on the project, and organizing the sample processing at the ODM Laboratory. Har-vey Thorleifson and Vesa Peuraniemi are appre-
ciated for revising the manuscript and providing valuable suggestions for improvements. Technical and laboratory staff of the Research Laboratory are acknowledged for their efforts.
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Lehtonen, M., Lahaye, Y., O’Brien, H., Lukkari, S., Marmo, J. & Sarala, P. 2014. NovTecEx-osatehtävä 2: Moreenin mineraloginen tutkimus – uusia menetelmiä indikaatto-rimineraaleihin perustuvaan malminetsintään. Geologi-cal Survey of Finland, archive report 102/2014. 17 p. (in Finnish)
Lehtonen, M. L., Marmo, J. S., Nissinen, A. J., Johanson, B. S. & Pakkanen, L. K. 2005. Glacial dispersal studies using indicator minerals and till geochemistry around two eastern Finland kimberlites. Journal of Geochemical Exploration 87 (1), 19−43.
McClenaghan, M. B. 2013. Application of indicator mineral methods to mineral exploration in Canada. Geological Survey of Finland, Lecture, September 11, 2013.
McClenaghan, M. B. & Kjarsgaard, B. A. 2007. Indicator mineral and surficial geochemical exploration met-hods for kimberlite in glaciated terrain, examples from Canada. In: Mineral Resources of Canada: A Synthesis of Major Deposit-types, District Metallogeny, the Evolu-tion of Geological Provinces and Exploration Methods. Geological Association of Canada, Special Publication 5, 983−1006.
McClenaghan, M. B. & Cabri, L. J. 2011. Gold and platinum group element indicator minerals in surficial sediments. Geochemistry: Exploration, Environment, Analysis 11, 251−263.
McClenaghan, M. B., Parkhill, M. A. Seaman, A. A., Pronk, A. G., Averill, S. A.., Rice, J. M. & Pyne, M. 2013. In-dicator mineral signatures of the Sisson W-Mo deposit, New Brunswick: Part 2 till. Geological Survey of Canada, Open File 7467.
Mutanen T. 1997. Geology and petrology of the Akanvaara and Koitelainen mafic layered intrusions and the Keivit-sa-Satovaara layered complex, northern Finland. Geolo-gical Survey of Finland, Bulletin 395.
Oviatt, N. M., McClenaghan, M. B., Paulen, R. C., Glee-son, S. A., Averill, S. A. & Paradis, S. 2013. Indicator minerals in till and bedrock samples from the Pine Point Mississippi Valley-type District, Northwest Territories. Geological Survey of Canada, Open File 7423.
Peuraniemi, V. 1990. Heavy minerals in glacial material. In: Kujansuu, R. & Saarnisto, M. (eds) Glacial Indicator Tra-cing. Rotterdam: A. A. Balkema, 165−185.
Sarala, P. 2015. Comparison of different techniques for ba-sal till sampling in mineral exploration. In: Sarala, P. (ed.) Novel technologies for greenfield exploration. Geological Survey of Finland, Special Paper 57, 11–22. (this journal)
Sarala, P. & Ojala, V. J. 2008. Implications of Complex Gla-cial Deposits for Till Geochemical exploration: Examples from the central Fennoscandian ice sheet. In: Stefánsson, Ó. (ed.) Geochemistry Research Advances, Chapter 1. New York: Nova Publishers, 1−29.
Sarapää, O., Al Ani, T., Lahti, S. I., Lauri, L. S., Sarala, P., Torppa, A. & Kontinen, A. 2013. Rare earth exploration potential in Finland. Journal of Geochemical Exploration 133, 25−41.
Stendal, H. & Theobald, P. K. 1996. Heavy-mineral concent-rates in geochemical exploration. In: Hale, M. & Plant, J. A. (eds) Handbook of Exploration Geochemistry, Vol. 6, Drainage Geochemistry, 85−225.
56
Geological Survey of Finland, Special Paper 57Marja Lehtonen, Yann Lahaye, Hugh O’Brien, Sari Lukkari, Jukka Marmo and Pertti Sarala
Appe
ndix
I. L
abtiu
m d
ata.
Lab
tium
ID
GT
K ID
gra
in s
ize
(µm
)
den
sity
(gcm
-3)
met
hod
L130
0765
6L1
3005
923
L130
0592
4L1
3005
925
L130
0591
1L1
3005
917
L130
0591
8L1
3005
918U
L130
0591
9L1
3005
912
L130
0591
4L1
3005
915
L130
0591
5UL1
3005
916
TPR
-1
TPR
-1TP
R-1
Ø 1
00-5
00 µ
m
Ø 6
3-10
0 µm
Ø
<63
µm
d
>3.
3d
>3.
3d
>3.
3
175X
310M
310M
310M
175X
310M
310M
310M
310M
175X
310M
310M
310M
310M
Na2
O%
0.25
10.
103
0.07
9
MgO
%1.
410
0.63
00.
492
Al2
O3
%12
.60
6.16
4.19
SiO
2%
24.5
012
.40
9.59
P2O
5%
0.13
20.
146
0.31
5
K2O
%0.
129
0.05
20.
041
CaO
%10
.29
4.30
3.34
TiO
2%
9.60
11.4
612
.79
11.8
818
.80
23.3
524
.19
27.5
222
.02
20.1
123
.85
25.1
923
.02
26.0
2
MnO
%0.
831.
171.
160.
921.
161.
541.
521.
811.
471.
021.
361.
391.
381.
37
Fe2O
3%
38.9
052
.00
54.4
0
S%
0.02
0<
0.24
<0.
24<
0.24
0.03
5<
0.24
<0.
24<
0.24
<0.
240.
032
<0.
24<
0.24
<0.
24<
0.24
Cl
%0.
012
0.00
60.
009
Sc
%0.
005
0.00
60.
006
0.00
60.
002
0.00
60.
006
0.00
60.
005
0.00
30.
006
0.00
70.
005
0.00
6
V%
0.06
10.
080
0.08
5
Cr
%0.
049
<0.
040
<0.
040
<0.
040
0.09
30.
083
0.07
80.
080
0.06
60.
125
0.10
40.
121
0.11
00.
111
Ni
%0.
005
0.00
40.
004
0.00
40.
007
0.00
70.
007
0.00
80.
007
0.01
00.
008
0.00
90.
009
0.00
9
Cu
%0.
002
0.00
60.
007
0.00
6<
0.00
20.
010
0.00
90.
011
0.00
9<
0.00
20.
010
0.01
10.
010
0.01
0
Zn
%0.
014
0.01
70.
019
0.01
70.
016
0.02
80.
027
0.03
60.
028
0.01
70.
027
0.02
90.
031
0.03
1
Ga
%<
0.00
2<
0.00
2<
0.00
2
As
%0.
014
<0.
020
<0.
020
<0.
020
0.03
4<
0.02
00.
028
0.03
6<
0.02
00.
029
<0.
020
<0.
020
0.02
50.
022
Rb
%0.
003
<0.
0005
0.00
10.
001
0.00
5<
0.00
05<
0.00
05<
0.00
05<
0.00
050.
006
<0.
0005
<0.
0005
<0.
0005
<0.
0005
Sr
%0.
088
0.07
00.
077
0.07
80.
032
0.02
60.
032
0.02
90.
029
0.02
40.
024
0.02
40.
023
0.02
2
Y%
0.01
70.
002
0.00
20.
002
0.02
90.
003
0.00
30.
006
0.00
40.
042
0.00
50.
003
0.00
30.
004
Zr
%0.
565
0.42
90.
673
0.37
42.
695
2.19
02.
440
2.47
02.
010
3.99
12.
740
3.21
02.
890
3.38
0
Nb
%0.
004
0.01
00.
011
0.00
80.
001
0.01
40.
014
0.01
40.
013
<0.
0007
0.01
30.
015
0.01
30.
015
Mo
%<
0.00
10.
009
0.01
7
Sn
%0.
005
0.00
10.
001
0.00
10.
006
0.00
10.
001
0.00
10.
001
0.00
50.
001
0.00
10.
001
0.00
1
Sb
%<
0.01
0.00
0<
0.00
01<
0.00
01<
0.01
0.00
10.
000
0.00
1<
0.00
01<
0.01
0.00
10.
003
0.00
30.
003
Ba
%0.
028
<0.
005
<0.
005
<0.
005
0.05
4<
0.00
50.
006
<0.
005
<0.
005
0.05
5<
0.00
5<
0.00
5<
0.00
5<
0.00
5
La%
0.01
80.
001
0.00
10.
001
0.03
8<
0.00
1<
0.00
1<
0.00
1<
0.00
10.
078
0.00
1<
0.00
1<
0.00
1<
0.00
1
Ce
%0.
043
0.00
50.
005
0.00
50.
070
0.00
50.
005
0.00
60.
006
0.15
40.
007
0.00
50.
005
0.00
5
Pb
%0.
010
0.02
80.
013
0.00
50.
025
0.03
50.
028
0.03
90.
026
0.08
80.
081
0.11
10.
104
0.13
2
Bi
%<
0.00
3<
0.00
05<
0.00
05<
0.00
050.
003
<0.
0005
<0.
0005
<0.
0005
<0.
0005
0.00
6<
0.00
05<
0.00
050.
002
0.00
3
Th%
0.01
5<
0.00
050.
001
<0.
0005
0.01
6<
0.00
05<
0.00
050.
001
0.00
10.
026
0.00
10.
001
<0.
0005
0.00
1
U%
0.00
30.
003
0.00
50.
002
0.00
50.
007
0.00
80.
008
0.00
60.
008
0.01
00.
011
0.01
00.
010
57
Geological Survey of Finland, Special Paper 57Novel technologies for indicator mineral-based exploration
Appe
ndix
II.
Opt
ical
mic
rosc
opy
resu
lts o
f OD
M a
nd G
TK p
roce
ssed
hea
vy m
iner
al co
ncen
trat
es.
The
num
bers
of a
cces
ory
min
eral
s are
nor
mal
ized
to 1
0 kg
of p
roce
ssed
till.
D
ata:
Ove
rbur
den
Dril
ling
Man
agem
ent L
td.
GT
K p
roce
ssed
Wei
ght
<
1 m
m t
able
fe
ed (k
g)
Mic
rosc
op
y 0.
25-1
.0 m
m:
min
eral
ass
emb
lag
eM
icro
sco
py
0.25
-1.0
m
m: a
cces
sori
es
Chal
co-
pyrit
ePy
rite
Low
Cr
-di
opsi
de
Ruby
Co
run-
dum
Sapp
hire
Co
run-
dum
Mn
ep
idot
eGa
hnite
Red
Rutil
eCh
rom
ite%
Go
ethi
te%
Ky
anite
%
Silli
ma-
nite
%
Tour
-m
alin
e
%
Stau
rolit
e%
Sp
es-
sarti
ne
%
Faya
lite
% O
px%
Ap
atite
%
Mon
azite
RM
_PO
S$-
2012
-36.
210
.9A
lman
din
e-ilm
enite
/sta
urol
ite-e
pid
ote
11
30
00
055
550
10Tr
Tr70
Tr0
Tr0
Tr
RM
_PO
S$-
2012
-39.
118
.5A
lman
din
e/ep
idot
e-st
auro
lite-
kyan
ite0
01
00
00
2210
80
15Tr
030
Tr0
0Tr
Tr
RM
_PO
S$-
2012
-41.
28.
3A
lman
din
e-ilm
enite
/ep
idot
e-st
auro
lite
10
00
00
048
720
8Tr
030
Tr0
00
0
RM
_PO
S$-
2012
-43.
38.
4A
lman
din
e/st
auro
lite-
epid
ote
00
00
00
3136
360
3Tr
050
Tr0
10
0
RM
_PO
S$-
2012
-48.
211
Alm
and
ine-
ilmen
ite/s
taur
olite
-ep
idot
e0
01
00
01
3673
05
Tr0
60Tr
0Tr
00
RM
_PO
S$-
2012
-55.
27.
5A
lman
din
e-ilm
enite
-hor
nble
nde/
ep
idot
e- s
taur
olite
01
00
00
053
53Tr
3Tr
020
Tr0
Tr0
0
RM
_PO
S$-
2012
-66.
119
.7H
emat
ite-a
lman
din
e-ilm
enite
/ st
auro
lite-
ep
idot
e-ky
anite
00
00
00
020
9Tr
20Tr
040
Tr0
Tr0
0
RM
_PO
S$-
2012
-77.
29.
5A
lman
din
e-ilm
enite
-hem
atite
/ep
idot
e- s
taur
olite
-kya
nite
00
00
00
063
32Tr
20Tr
040
Tr0
Tr0
0
RM
_PO
S$-
2012
-82.
122
.2A
lman
din
e-he
mat
ite-i
lmen
ite/
epid
ote-
sta
urol
ite0
00
00
00
2768
Tr8
Tr0
30Tr
0Tr
00
RM
_PO
S$-
2012
-97.
211
.6A
lman
din
e-he
mat
ite/
epid
ote-
stau
rolit
e0
00
00
00
3434
Tr5
Tr0
40Tr
0Tr
00
OD
M p
roce
ssed
Wei
ght
<
2 m
m t
able
fe
ed (k
g)
Mic
rosc
op
y 0.
25-2
.0 m
m:
min
eral
ass
emb
lag
eM
icro
sco
py
0.25
-1.0
mm
: acc
esso
ries
Chal
co-
pyrit
ePy
rite
Low
Cr
-di
opsi
de
Ruby
Co
run-
dum
Sapp
hire
Co
run-
dum
Mn
epid
ote
Gahn
iteRe
d Ru
tile
Chro
mite
%
Goet
hite
%
Kyan
ite%
Si
llim
a-ni
te
%
Tour
-m
alin
e
%
Stau
rolit
e%
Spe
s-sa
rtine
%
Faya
lite
%
Opx
%
Apat
ite%
M
onaz
ite
RM
_PO
S$-
2012
-36.
119
.2A
lman
din
e-ilm
enite
/sta
urol
ite-e
pid
ote
01
00
00
031
420
123
070
Tr0
Tr0
Tr
RM
_PO
S$-
2012
-39.
416
Alm
and
ine/
epid
ote-
stau
rolit
e0
01
00
00
3894
Tr4
Tr0
15Tr
0Tr
00
RM
_PO
S$-
2012
-41.
117
.1A
lman
din
e/ep
idot
e-st
auro
lite
01
20
00
158
88Tr
10Tr
Tr15
Tr0
Tr0
Tr
RM
_PO
S$-
2012
-43.
211
.8A
lman
din
e/st
auro
lite-
epid
ote
03
00
00
4225
19Tr
5Tr
Tr60
Tr0
Tr0
0
RM
_PO
S$-
2012
-48.
111
.3A
lman
din
e-ilm
enite
/sta
urol
ite-e
pid
ote
01
00
00
688
106
Tr6
10
50Tr
Tr
(400
gr)
Tr0
Tr
RM
_PO
S$-
2012
-55.
113
.7A
lman
din
e-ilm
enite
-hor
nble
nde/
ep
idot
e- s
taur
olite
00
10
00
129
44Tr
TrTr
Tr30
Tr0
Tr0
0
RM
_PO
S$-
2012
-66.
414
.6A
lman
din
e-he
mat
ite-i
lmen
ite-
horn
ble
nde/
sta
urol
ite-e
pid
ote-
kyan
ite0
00
00
00
6834
Tr25
TrTr
40Tr
0Tr
0Tr
RM
_PO
S$-
2012
-77.
4R17
.3A
lman
din
e-ilm
enite
/ ep
idot
e-st
auro
lite-
kya
nite
00
21
00
029
35Tr
15Tr
Tr40
Tr0
Tr0
0
RM
_PO
S$-
2012
-82.
416
.6A
lman
din
e-ho
rnb
lend
e-he
mat
ite-
ilmen
ite/
epid
ote-
stau
rolit
e0
01
00
00
3615
1Tr
31
020
Tr0
Tr0
0
RM
_PO
S$-
2012
-97.
121
.5H
emat
ite-a
lman
din
e/st
auro
lite-
epid
ote
00
10
00
028
28Tr
10Tr
Tr70
Tr0
Tr0
0
58
Geological Survey of Finland, Special Paper 57Marja Lehtonen, Yann Lahaye, Hugh O’Brien, Sari Lukkari, Jukka Marmo and Pertti Sarala
Appendix III. Gold and PGM.
OVERBURDEN DRILLING MANAGEMENT LIMITEDSample Number Panned
Yes/NoDimensions (microns) Number of Visible Gold Grains -0.25 mm
Nonmag HMC
Weight
Calculated V.G. Assay in 0.25 mm
HMC
Metallic Minerals in Pan Concentrate
Thickness (M*/C**) Width Length Reshaped Modified Pristine Total (g) (ppb)
RM_POS$-2012-36.1 Yes 3 C 15 15 2 1 3
5 C 25 25 4 4
8 C 25 50 5 1 6 1 native platinum (50µm).
10 C 25 75 1 1 3 sperrylite (15-50µm).
10 C 50 50 2 2
20 C 100 100 1 1
50 M 200 250 1 1
18 162.4 133
RM_POS$-2012-39.4 Yes 3 C 15 15 2 2
5 C 25 25 1 1
10 C 25 75 1 1 1 native platinum (50µm).
13 C 50 75 1 1
5 352.8 2
RM_POS$-2012-41.1 Yes 3 C 15 15 1 1
8 C 25 50 1 1 2 grains sperrylite (25µm).
10 C 25 75 1 1
10 C 50 50 1 1 2
13 C 50 75 3 3
150 M 250 450 1 1
9 116.3 1200
RM_POS$-2012-43.2 Yes 3 C 15 15 1 1 2
5 C 25 25 2 2
8 C 25 50 4 4
13 C 25 100 1 1
10 C 50 50 1 1
13 C 50 75 2 2
15 C 75 75 1 1
13 58.2 40
RM_POS$-2012-48.1 Yes 3 C 15 15 2 1 3
5 C 25 25 5 1 6 2 grains sperrylite (15-25µm).
8 C 25 50 6 6
10 C 50 50 5 5
13 C 50 75 1 1
15 C 50 100 2 2
23 92.5 35
RM_POS$-2012-55.1 Yes 3 C 15 15 1 1
5 C 25 25 4 4
10 C 50 50 2 2
15 C 50 100 1 1
20 C 75 125 1 1
9 87.3 30
59
Geological Survey of Finland, Special Paper 57Novel technologies for indicator mineral-based exploration
Sample Number Panned Yes/No
Dimensions (microns) Number of Visible Gold Grains -0.25 mm Nonmag
HMC Weight
Calculated V.G. Assay in 0.25 mm
HMC
Metallic Minerals in Pan Concentrate
Thickness (M*/C**) Width Length Reshaped Modified Pristine Total (g) (ppb)
5 C 25 25 4 4
8 C 25 50 2 2 1 sperrylite (25µm)
10 C 50 50 3 3
13 C 50 75 1 1
18 C 50 125 1 1
18 C 75 100 1 1
20 C 75 125 2 2
20 84.9 74
RM_POS$-2012-77.4R Yes 5 C 25 25 6 6
8 C 25 50 3 3
10 C 50 50 2 2
13 C 50 75 1 1
15 C 75 75 1 1
20 C 100 100 1 1
14 169.1 19
RM_POS$-2012-82.4 Yes 3 C 15 15 2 1 3
5 C 25 25 6 2 8
8 C 25 50 2 2
10 C 50 50 3 3
13 C 50 75 3 1 4
15 C 75 75 1 1
25 C 125 125 1 1
22 123.6 48
RM_POS$-2012-97.1 Yes 3 C 15 15 12 12
5 C 25 25 11 11 1 grain sperrylite (25µm).
8 C 25 50 9 9
10 C 25 75 2 2
10 C 50 50 6 1 7
13 C 50 75 1 1
15 C 50 100 2 2
20 C 50 150 1 1
18 C 75 100 3 3
20 C 100 100 1 1
49 244.7 43
*) M = Actual measured thickness of grain (microns)
**) C = Thickness of grain (microns) calculated from measured width and length
Appendix III. Cont.
60
Geological Survey of Finland, Special Paper 57Marja Lehtonen, Yann Lahaye, Hugh O’Brien, Sari Lukkari, Jukka Marmo and Pertti Sarala
Appe
ndix
IV.
HR-
SC-I
CPM
S da
ta.
pp
mp
pm
pp
mp
pm
pp
mp
pm
pp
mp
pm
pp
mp
pm
pp
mp
pm
pp
mp
pm
pp
mp
pm
pp
mp
pm
pp
m
ID#
Sam
ple
co
de
Sam
ple
typ
eLi
Be
Sc
VC
rC
oN
iC
uZ
nG
aA
sR
bS
rY
Nb
Mo
Ru
Pd
Ag
1aG
K_P
OS
$-20
12-4
4.1
till <
0.06
3 m
m35
55.
246
428
752
9537
726
336
273
5.4
175
396
4323
3.26
0.00
10.
003
0.4
2aG
K_P
OS
$-20
12-4
7.2
till <
0.06
3 m
m11
33.
430
306
587
4921
013
724
755
5.7
9046
028
171.
650.
000
0.00
30.
3
3aG
K_P
OS
$-20
12-8
2.1
till <
0.06
3 m
m10
3.1
2433
572
345
167
3296
381.
127
352
3019
0.46
0.00
00.
003
0.2
4aG
K_P
OS
$-20
12-8
3.4
till <
0.06
3 m
m50
3.7
3749
663
856
207
162
8974
2.6
216
142
5018
1.13
0.00
00.
004
0.2
5aG
K_P
OS
$-20
12-9
7.3
till <
0.06
3 m
m17
3.5
3036
160
544
158
3590
451.
238
309
3224
0.43
0.00
00.
003
0.2
1bG
K_P
OS
$-20
12-4
4.1
HM
till,
HM
S, <
0.06
3 m
m89
2.8
209
865
2239
8914
516
764
920
331
17.0
440
1190
558
9.93
0.00
10.
073
14.8
2bG
K_P
OS
$-20
12-4
7.2
HM
till,
HM
S, <
0.06
3 m
m14
22.
016
412
4939
6110
720
911
510
5422
230
5.8
733
734
468
6.15
0.00
10.
059
8.4
3bG
K_P
OS
$-20
12-8
2.1
HM
til
l, H
MS
, <0.
063
mm
224.
212
117
3171
6010
335
070
486
867
8.3
801
310
256
3.07
0.00
10.
021
2.9
4bG
K_P
OS
$-20
12-8
3.4
HM
till,
HM
S, <
0.06
3 m
m26
1.8
122
1925
5052
7921
998
420
788
21.2
520
368
411
3.97
0.00
10.
024
6.5
5bG
K_P
OS
$-20
12-9
7.3
HM
till,
HM
S, <
0.06
3 m
m33
2.2
110
1989
4627
8419
678
397
817
10.2
656
334
306
3.42
0.00
10.
023
4.2
1cR
M_P
OS
$-20
12-4
4.2
till,
pre
con,
HM
S, <
0.06
3 m
m73
3.7
244
630
1320
7683
139
579
443
6614
.534
023
3265
28.
970.
000
0.14
538
.5
2cR
M_P
OS
$-20
12-4
7.2
till,
pre
con,
HM
S, <
0.06
3 m
m10
42.
219
073
215
0197
7413
410
3746
969
5.7
367
2074
620
5.59
0.00
00.
122
23.0
3cR
M_P
OS
$-20
12-8
2.1
till,
pre
con,
HM
S, <
0.06
3 m
m14
1.8
7915
4274
2495
104
140
484
8511
8.7
273
289
265
2.48
0.00
10.
019
7.0
4cR
M_P
OS
$-20
12-8
3.2
till,
pre
con,
HM
S, <
0.06
3 m
m19
1.7
133
1665
4410
9310
115
150
417
524
10.8
281
607
317
3.50
0.00
10.
040
18.2
5cR
M_P
OS
$-20
12-9
7.2
till,
pre
con,
HM
S, <
0.06
3 m
m17
3.8
134
1804
1238
291
113
188
431
8911
19.4
452
222
156
2.11
0.00
00.
016
4.1
6R
M_P
OS
$-20
12-3
6.2
till,
pre
con,
HM
S, <
0.06
3 m
m25
1.8
5416
0944
4182
7812
447
311
212
0.8
186
277
284
3.16
0.00
10.
019
18.1
7R
M_P
OS
$-20
12-3
8.1
till,
pre
con,
HM
S, <
0.06
3 m
m18
1.6
5914
1260
8591
7011
957
110
710
0.7
333
265
255
3.93
0.00
10.
018
15.6
8R
M_P
OS
$-20
12-3
9.1
till,
pre
con,
HM
S, <
0.06
3 m
m16
1.4
101
1348
4276
8092
146
500
138
168.
633
152
527
23.
240.
001
0.03
511
.6
9R
M_P
OS
$-20
12-4
1.2
till,
pre
con,
HM
S, <
0.06
3 m
m15
0.9
112
1496
5555
8760
172
625
217
293.
311
599
935
74.
350.
001
0.06
117
.0
10R
M_P
OS
$-20
12-4
3.3
till,
pre
con,
HM
S, <
0.06
3 m
m51
1.5
149
1044
2560
9466
146
1034
427
606.
236
621
5241
64.
890.
001
0.14
218
.1
11R
M_P
OS
$-20
12-4
8.2
till,
pre
con,
HM
S, <
0.06
3 m
m25
1.5
134
1178
3841
111
141
159
710
132
185.
130
560
236
64.
400.
001
0.03
915
.4
12R
M_P
OS
$-20
12-5
5.2
till,
pre
con,
HM
S, <
0.06
3 m
m20
1.4
105
1621
5003
9172
124
497
107
143.
729
449
833
74.
270.
001
0.03
316
.0
13R
M_P
OS
$-20
12-6
6.1
till,
pre
con,
HM
S, <
0.06
3 m
m17
1.6
118
1354
2056
5452
9726
110
413
6.3
465
439
210
3.38
0.00
00.
032
17.3
14R
M_P
OS
$-20
12-7
7.2
till,
pre
con,
HM
S, <
0.06
3 m
m24
1.4
9912
7441
5684
5914
655
511
214
4.9
298
440
376
3.16
0.00
10.
028
12.9
15R
M_P
OS
$-20
12-8
5.2
till,
pre
con,
HM
S, <
0.06
3 m
m22
1.5
9517
3432
7484
8013
449
311
515
5.8
267
431
327
3.12
0.00
00.
030
11.6
16R
M_J
OV
$-20
12-2
.1til
l, p
reco
n, H
MS
, <0.
063
mm
301.
714
111
0050
1387
7213
946
885
83.
036
337
522
55.
110.
001
0.03
131
.7
17R
M_H
AH
1-20
13-1
.1til
l, p
reco
n, H
MS
, <0.
063
mm
232.
248
1276
2436
380
5096
187
526
808
6.3
270
284
256
2.88
0.00
10.
021
7.5
18R
M_H
AH
1-20
13-5
.1til
l, p
reco
n, H
MS
, <0.
063
mm
741.
911
697
720
3643
030
659
213
2827
040
2.8
429
1250
288
12.5
20.
001
0.09
115
.2
19R
M_H
AH
1-20
12-5
05.1
till,
pre
con,
HM
S, <
0.06
3 m
m19
1.2
6611
8033
7710
391
254
601
143
162.
337
836
026
16.
000.
001
0.02
513
.4
20R
M_H
AH
1-20
12-5
09.1
till,
pre
con,
HM
S, <
0.06
3 m
m10
1.0
4681
923
5178
5815
357
811
012
0.3
275
292
143
2.87
0.00
10.
022
13.1
+ :
Con
cent
atio
ns t
oo h
igh
61
Geological Survey of Finland, Special Paper 57Novel technologies for indicator mineral-based exploration
Appe
ndix
IV.
Con
t.p
pm
pp
mp
pm
pp
mp
pm
pp
mp
pm
pp
mp
pm
pp
mp
pm
pp
mp
pm
pp
mp
pm
pp
mp
pm
pp
mp
pm
ID#
Sam
ple
co
de
Sam
ple
typ
eC
dS
nS
bC
sB
aLa
Ce
Nd
Sm
Eu
Sm
Eu
Gd
Tb
Dy
Ho
Er
Tm
Yb
1aG
K_P
OS
$-20
12-4
4.1
till <
0.06
3 m
m0.
56.
60.
1140
.65
1648
116
243
106
193
193
162
92
41
3
2aG
K_P
OS
$-20
12-4
7.2
till <
0.06
3 m
m0.
63.
30.
197.
2316
9894
186
8014
314
312
17
13
02
3aG
K_P
OS
$-20
12-8
2.1
till <
0.06
3 m
m0.
23.
30.
260.
5870
331
6731
62
72
61
61
30
3
4aG
K_P
OS
$-20
12-8
3.4
till <
0.06
3 m
m0.
26.
20.
336.
0717
5310
727
193
174
174
142
102
51
4
5aG
K_P
OS
$-20
12-9
7.3
till <
0.06
3 m
m0.
23.
90.
400.
8670
747
8538
72
82
71
61
30
3
1bG
K_P
OS
$-20
12-4
4.1
HM
till,
HM
S, <
0.06
3 m
m8.
522
.10.
694.
2312
5+
+56
2295
110
492
198
697
7831
247
110
1385
2bG
K_P
OS
$-20
12-4
7.2
HM
till,
HM
S, <
0.06
3 m
m6.
120
.81.
660.
7080
++
5113
839
144
825
140
623
6927
038
8710
61
3bG
K_P
OS
$-20
12-8
2.1
HM
til
l, H
MS
, <0.
063
mm
2.2
24.8
1.85
0.20
6555
911
2251
190
1991
1978
1158
1132
531
4bG
K_P
OS
$-20
12-8
3.4
HM
till,
HM
S, <
0.06
3 m
m4.
325
.61.
750.
8411
810
5920
6891
514
926
156
2612
015
7414
396
40
5bG
K_P
OS
$-20
12-9
7.3
HM
till,
HM
S, <
0.06
3 m
m2.
827
.82.
320.
3673
750
1473
656
111
2211
621
9512
6513
355
35
1cR
M_P
OS
$-20
12-4
4.2
till,
pre
con,
HM
S, <
0.06
3 m
m19
.014
.30.
572.
4616
2+
+14
410
2436
244
2370
233
1771
192
722
9519
320
125
2cR
M_P
OS
$-20
12-4
7.2
till,
pre
con,
HM
S, <
0.06
3 m
m13
.316
.21.
240.
5670
++
1468
724
6940
624
1138
917
8119
070
393
187
1910
9
3cR
M_P
OS
$-20
12-8
2.1
till,
pre
con,
HM
S, <
0.06
3 m
m4.
617
.51.
020.
1711
719
8139
2116
4826
036
261
3518
619
7311
294
24
4cR
M_P
OS
$-20
12-8
3.2
till,
pre
con,
HM
S, <
0.06
3 m
m10
.423
.80.
800.
4387
++
4518
680
8766
184
458
4517
025
597
46
5cR
M_P
OS
$-20
12-9
7.2
till,
pre
con,
HM
S, <
0.06
3 m
m2.
590
.40.
780.
3011
310
8920
8885
013
223
135
2299
1148
821
319
6R
M_P
OS
$-20
12-3
6.2
till,
pre
con,
HM
S, <
0.06
3 m
m11
.419
.80.
960.
0837
2859
+24
3037
454
359
5426
128
110
1743
637
7R
M_P
OS
$-20
12-3
8.1
till,
pre
con,
HM
S, <
0.06
3 m
m10
.020
.51.
150.
0342
2372
+20
4231
939
317
3922
224
101
1642
637
8R
M_P
OS
$-20
12-3
9.1
till,
pre
con,
HM
S, <
0.06
3 m
m7.
718
.31.
030.
2110
440
09+
3506
529
5651
957
363
3713
921
516
39
9R
M_P
OS
$-20
12-4
1.2
till,
pre
con,
HM
S, <
0.06
3 m
m11
.218
.20.
900.
2129
++
6700
1101
146
1065
139
787
8634
247
100
1054
10R
M_P
OS
$-20
12-4
3.3
till,
pre
con,
HM
S, <
0.06
3 m
m11
.737
.00.
830.
8650
++
1306
722
0525
021
2824
416
1517
768
493
183
1798
11R
M_P
OS
$-20
12-4
8.2
till,
pre
con,
HM
S, <
0.06
3 m
m9.
669
.31.
170.
2859
3854
+32
6850
663
488
6135
438
150
2357
750
12R
M_P
OS
$-20
12-5
5.2
till,
pre
con,
HM
S, <
0.06
3 m
m9.
730
.01.
420.
1541
2782
+23
7136
949
365
4826
629
119
1950
746
13R
M_P
OS
$-20
12-6
6.1
till,
pre
con,
HM
S, <
0.06
3 m
m10
.119
.11.
550.
1980
1880
3709
1618
270
5126
751
207
2396
1644
643
14R
M_P
OS
$-20
12-7
7.2
till,
pre
con,
HM
S, <
0.06
3 m
m7.
720
.60.
800.
2442
2826
+24
7238
647
375
4626
628
110
1744
639
15R
M_P
OS
$-20
12-8
5.2
till,
pre
con,
HM
S, <
0.06
3 m
m7.
021
.71.
330.
2246
3063
+25
8940
554
392
5428
229
114
1743
637
16R
M_J
OV
$-20
12-2
.1til
l, p
reco
n, H
MS
, <0.
063
mm
20.0
38.6
1.00
0.18
5615
4530
9313
5823
940
235
3919
523
110
2160
970
17R
M_H
AH
1-20
13-1
.1til
l, p
reco
n, H
MS
, <0.
063
mm
4.7
19.8
0.95
0.22
192
1484
2897
1217
194
2819
728
145
1671
1233
429
18R
M_H
AH
1-20
13-5
.1til
l, p
reco
n, H
MS
, <0.
063
mm
11.2
18.6
2.46
0.38
80+
+74
3312
1316
511
7815
790
210
039
857
124
1378
19R
M_H
AH
1-20
12-5
05.1
till,
pre
con,
HM
S, <
0.06
3 m
m8.
618
.60.
840.
2149
3473
+33
1248
038
466
3730
630
113
1743
533
20R
M_H
AH
1-20
12-5
09.1
till,
pre
con,
HM
S, <
0.06
3 m
m8.
511
.90.
410.
0332
2853
+26
6137
732
370
3124
924
9215
385
30
+ :
Con
cent
atio
ns t
oo h
igh
62
Geological Survey of Finland, Special Paper 57Marja Lehtonen, Yann Lahaye, Hugh O’Brien, Sari Lukkari, Jukka Marmo and Pertti Sarala
Appe
ndix
IV.
Con
t.p
pm
pp
mp
pm
pp
mp
pm
pp
mp
pm
pp
mp
pm
pp
mp
pm
pp
mp
pm
ID#
Sam
ple
co
de
Sam
ple
typ
eLu
Hf
TaW
Re
Pt
Au
Hg
Tl
Pb
Bi
Th
U
1aG
K_P
OS
$-20
12-4
4.1
till <
0.06
3 m
m0
201
220.
001
0.03
0.01
0.25
2.06
394
2612
2aG
K_P
OS
$-20
12-4
7.2
till <
0.06
3 m
m0
131
50.
002
0.02
0.08
0.06
0.86
423
207
3aG
K_P
OS
$-20
12-8
2.1
till <
0.06
3 m
m0
101
10.
003
0.02
0.00
0.02
0.33
150
82
4aG
K_P
OS
$-20
12-8
3.4
till <
0.06
3 m
m1
120
10.
002
0.02
0.00
0.01
1.26
170
2211
5aG
K_P
OS
$-20
12-9
7.3
till <
0.06
3 m
m0
122
20.
002
0.02
0.00
0.04
0.43
150
104
1bG
K_P
OS
$-20
12-4
4.1
HM
till,
HM
S, <
0.06
3 m
m14
894
6924
50.
033
0.16
1.89
2.79
0.45
234
6210
1133
8
2bG
K_P
OS
$-20
12-4
7.2
HM
till,
HM
S, <
0.06
3 m
m10
518
4467
0.02
50.
090.
110.
930.
6823
659
1181
226
3bG
K_P
OS
$-20
12-8
2.1
HM
til
l, H
MS
, <0.
063
mm
516
618
130.
010
0.03
0.05
0.21
0.27
462
153
27
4bG
K_P
OS
$-20
12-8
3.4
HM
till,
HM
S, <
0.06
3 m
m7
398
3616
0.01
10.
060.
350.
280.
2674
231
461
5bG
K_P
OS
$-20
12-9
7.3
HM
till,
HM
S, <
0.06
3 m
m6
252
2317
0.01
00.
040.
070.
270.
9456
124
843
1cR
M_P
OS
$-20
12-4
4.2
till,
pre
con,
HM
S, <
0.06
3 m
m20
2152
101
261
0.04
60.
395.
012.
720.
3158
721
110
0082
1
2cR
M_P
OS
$-20
12-4
7.2
till,
pre
con,
HM
S, <
0.06
3 m
m17
1516
6710
70.
039
0.27
0.24
1.42
0.15
710
224
225
677
3cR
M_P
OS
$-20
12-8
2.1
till,
pre
con,
HM
S, <
0.06
3 m
m4
422
2211
0.00
70.
140.
070.
190.
1411
51
593
68
4cR
M_P
OS
$-20
12-8
3.2
till,
pre
con,
HM
S, <
0.06
3 m
m8
1106
3017
0.01
40.
240.
140.
250.
1428
01
494
175
5cR
M_P
OS
$-20
12-9
7.2
till,
pre
con,
HM
S, <
0.06
3 m
m3
215
1310
0.00
50.
060.
050.
210.
2795
125
439
6R
M_P
OS
$-20
12-3
6.2
till,
pre
con,
HM
S, <
0.06
3 m
m6
1055
2412
0.01
20.
900.
130.
170.
0716
92
264
150
7R
M_P
OS
$-20
12-3
8.1
till,
pre
con,
HM
S, <
0.06
3 m
m6
950
244
0.01
10.
720.
120.
090.
0816
46
351
146
8R
M_P
OS
$-20
12-3
9.1
till,
pre
con,
HM
S, <
0.06
3 m
m6
728
249
0.01
30.
570.
100.
140.
1024
12
1082
154
9R
M_P
OS
$-20
12-4
1.2
till,
pre
con,
HM
S, <
0.06
3 m
m8
1120
4021
0.01
90.
630.
140.
260.
0752
064
443
430
10R
M_P
OS
$-20
12-4
3.3
till,
pre
con,
HM
S, <
0.06
3 m
m15
1130
4158
0.03
50.
610.
150.
710.
1665
25
409
694
11R
M_P
OS
$-20
12-4
8.2
till,
pre
con,
HM
S, <
0.06
3 m
m8
994
2919
0.01
40.
470.
120.
270.
1021
63
804
161
12R
M_P
OS
$-20
12-5
5.2
till,
pre
con,
HM
S, <
0.06
3 m
m8
981
2715
0.01
40.
430.
130.
210.
1416
62
861
138
13R
M_P
OS
$-20
12-6
6.1
till,
pre
con,
HM
S, <
0.06
3 m
m7
971
1710
0.01
30.
460.
150.
220.
1410
82
547
105
14R
M_P
OS
$-20
12-7
7.2
till,
pre
con,
HM
S, <
0.06
3 m
m6
807
3513
0.01
10.
280.
120.
180.
0816
71
794
120
15R
M_P
OS
$-20
12-8
5.2
till,
pre
con,
HM
S, <
0.06
3 m
m6
677
2714
0.01
20.
200.
100.
240.
0717
61
742
108
16R
M_J
OV
$-20
12-2
.1til
l, p
reco
n, H
MS
, <0.
063
mm
1318
1222
90.
019
1.85
0.18
0.13
0.12
147
136
125
2
17R
M_H
AH
1-20
13-1
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l, p
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n, H
MS
, <0.
063
mm
539
220
150.
011
0.59
0.17
0.22
0.13
862
240
62
18R
M_H
AH
1-20
13-5
.1til
l, p
reco
n, H
MS
, <0.
063
mm
1286
838
490.
038
1.07
0.15
0.75
2.43
487
4057
140
0
19R
M_H
AH
1-20
12-5
05.1
till,
pre
con,
HM
S, <
0.06
3 m
m5
847
2829
0.05
41.
040.
140.
400.
1242
12
715
204
20R
M_H
AH
1-20
12-5
09.1
till,
pre
con,
HM
S, <
0.06
3 m
m5
737
111
0.01
11.
010.
080.
020.
1423
01
513
123
+ :
Con
cent
atio
ns t
oo h
igh