2. precious metals au-ag
DESCRIPTION
Metals Mineralogy: Au (Gold) and AgTRANSCRIPT
GEOLOGI MINERAL LOGAM
INDRA SANJAYA
Precious Metals (Au – Ag)
China South Africa United States
Australia Indonesia Peru Russia Canada PNG Ghana
2007
Gold (Tonnes) 276 272 255 251 171 167 153 93 67 63
25
75
125
175
225
275
325
375
276 272 255 251
171 167 153
93 67 63
TOP TENS GOLD PRODUCERS (2007) Source: USGS 2007 Mineral Year Book
Go
ld P
rod
uct
ion
(To
nn
es)
China Australia United States
South Africa Russia Peru Indonesia Ghana Canada Uzbekistan
2010
Gold (Tonnes) 341 266 240 190 190 170 120 100 90 90
25
75
125
175
225
275
325
375 341
266 240
190 190 170
120 100 90 90
TOP TENS GOLD PRODUCERS (2010) Source: Gold Mining Journal 2011
Go
ld P
rod
uct
ion
(To
nn
es)
Total: 1,797 tonnes
Total: 1,768 tonnes
(Frimmel, 2008)
GOLD PRODUCTION BY DEPOSIT TYPE
GOLD OVERVIEW
GOLD OVERVIEW
GOLD BEARING MINERALS
KETERDAPATAN ENDAPAN EMAS
High‐, intermediate‐ and low‐sulphidation epithermal Au‐Ag
Porphyry & Skarn deposits Intrusion‐related base metal‐Au Intrusion‐related Au Carlin-type sediment hosted Au deposit Orogenic Deposits Placer
SISTEM HIDROTERMAL MAGMATIK
Corbett and Leach,1998)
lithosphere-scale environments for the formation of the principal gold deposit types ( Groves et al., 2005).
DEPOSIT MODEL (Corbett, 2005)
(Van Leuween, 2011)
Epthermal high sulphidation
KarakteristikMineralogi berupa enargit, pirit, kovelit, emas
murni, elektrum logam dasar sulfida, garam sulfat, dan telurid,
Logam yang dihasilkan berupa emas, perak dan tembaga,
Temperatur 200°-300°C,Salinitas 1-6 wt. % NaCl eg.,Didominasi oleh air magmatik.Kelompok argilik lanjut dicirikan oleh hadirnya
mineral alunit, kaolinit, pirofilit, belereng murni, diaspor, kuarsa, zunyit, dan barit (Sillitoe dan Bonham, 1990).Corbett and Leach,1998)
HS EPITHERMAL Au – Ag (Motomboto)
Motomboto can be classified as a structurally controlled system. Alteration and mineralization are apparently controlled by rift faults parallel to the Neogene arc (Kavalieris et al., 1992)
HS EPITHERMAL Au – Ag (Cabang Kiri)
Cabang Kiri can be classified as a porphyry related system. It shows progressive cooling and decrease in fluid pH away from the porphyry intrusion (Perello, 1994)
HS EPITHERMAL Au – Ag (Binabase-Bawone)
Binabase‐Bawone display aspects of both lithological and structural control (van Leuween, 2011)
HS EPITHERMAL Au – Ag (Binabase-Bawone)
Epthermal intermediate sulphidation
KarakteristikMineralization styles stockwork, disseminated, vein
and breccia‐hostedgold mineralizationcolloform banded quartz + adularia + carbonateMineralogy chalcopyrite-covellite‐galena sphalerite
and tetrahedrite-tennantite‐molybdenite (Einaudi et al., 2003)
Relationship with andesite to rhyodacite rocks
Epthermal intermediate sulphidation
KarakteristikMineralization styles stockwork, disseminated, vein
and breccia‐hostedgold mineralizationcolloform banded quartz + adularia + carbonateMineralogy chalcopyrite-covellite‐galena sphalerite
and tetrahedrite-tennantite‐molybdenite (Einaudi et al., 2003)
Relationship with andesite to rhyodacite rocks
IS EPITHERMAL Au – Ag (Doup)
A resource of about 12 Mt @ 2.09 g/t Au and 4.4 g/t Ag. The mineralization forms a pipe‐like body that extends to a depth of at least 200m, and is 100 by 200m in diameter elongated in a NW‐SE direction
Epthermal low sulphidation
KarakteristikBatuan induk terdiri dari andesit kalk-alkali, dasit,
riodasit atau riolit,Mineralogi berupa pirit, emas, hematit, tennantit,
molibdenum, dan tungsten,Alterasi yang terjadi yaitu kuarsa-adularia, karbonat,
dan serisit,Salinitas rendah (0-5 % NaCl),Asal larutan dari air meteorik dan air magmatik.
Vein distribution: eg. Kapitu prospect
Grade of Kapitu vein:
5.5m @ 4.4 g/t Au 1m @ 7.87 g/t Au 6m @ 8.77 g/t Au 1m @ 40.3 g/t Au 2m @ 5.59 g/t Au 1m @ 8.26 g/t Au
Low-sulphidation epithermal Au veins
Bonanza zone
Vein texturesBonanza zone
Kapitu veins
B. CU-AU PORPHYRY DEPOSITS
PERIPHERALC cp -G n-Sp-Au-Ag PERIPHERAL
C cp -G n-Sp-Au-Ag
LOW PYRITESHELLP y ~2%
Mag>Py
PYR ITES H E LLPy ~10%Ccp 0.1-3%Mo rare
M ag >Py& C cp
ORE SHELLPy 1 %C cp 1-3%M o 0 .03%
LOW GRADECORElow tota lCcp-Py-Mo
?
?
SAN M ANUEL FAU LT
KALAMAZOOSEGMENT
SAN M ANUELSEGMENT
Propylitic(Chl-Ep-Carb)
A dul-A b
ArgillicQ tz-K ln-C h l
PhyllicQ tz-S er-P y
PotassicQ tz-K fs-B t-+ S er+A n h
Q tz-S er-C h l-K fs
Chl-Ser-Ep-M ag
?
?
?
??
A
Cu-(Au) porphyry vein-veinlet system
a) Collahuasi/Chileb) Grasberg/Irian Jaya
a
b
Buladigun Cu-Au porphyry,North Sulawesi
Alteration styles
Carlin-type sediment hosted Au deposit
Karakteristik
1. Batuan pembawa berupa sedimen karbonat
2. Kandungan Au/Ag relatif tinggi
3. Pengkayaan unsur As, Sb, Hg yang tinggi
4. Invisible atau nosseum gold
5. Kandungan logam dasar yang rendah, dan kehadiran urat kuarsa dalam jumlah minimal
6. Batuan karbonat sebagai batuan pembawa mengandung karbon sebanyak 0.5 % berat.
Sumber: (Bagby & Berger, 1986); Ferdock (2002)
Carlin-style sediment hosted Au deposit
Mesel, Ratatotok(North
Sulawesi)
(Hendri & Farmer, 1997)
Carlin-style sediment hosted Au deposit
Yance-Leon Prospect, Mesel, Ratatotok (North Sulawesi)
Fresh limestone Silicified limestone
Argillic alterationRealgar, cinnabar (late stage)
Intrusion Related Au
Conceptual model for mineralization types in The Western Sulawesi Province (van Leuween, 2011)
Characteristics Orogenic belts, (collisional to postcollisonal)
convergent plate margin settings, extensional back-arc environments.
Presence of weakly reduced to moderately oxidised, intermediate to felsic magmatism.
Gold ± Bi, As, W, Mo, Sb, Te occurs in: single, planar, sheeted and stockwork quartz veins
Base metal contents are highly variable from almost absent to assemblages of Cu-Zn-Pb-As. Bi minerals may be well developed.
Alteration is variable in both style and intensity.
1. The gold is associated with sulphur‐poor, sodic‐rich fluids.
2. Albite‐pyrite‐silica±carbonate alteration associated with deformation and metamorphism in the older basement lithologies
3. Mineralization is typically hosted within a flysch sequence
4. Gold is usually associated with abundant quartz veining and silica‐albite‐pyrite alteration
(Gustavson, 2007)
AWAK MAS GOLD DEPOSITS
Querubin & Walters, 2011
POBOYA GOLD DEPOSIT(Wajdi dkk, 2011)
POBOYA GOLD DEPOSIT(Wajdi dkk, 2011)
POBOYA GOLD DEPOSIT
(Wajdi dkk, 2011)
ENDAPAN Au MESOTERMAL Endapan mesotermal merupakan salah satu
tipe endapan hidrotermal yang terbentuk pada lingkungan batuan metamorfik,
Karakteristik endapan mesotermal:Urat emas–kuarsa yang terdapat di sekitar
batuan metamorfikEkstraksi Au dari batuan samping melalui air
kristal (H2O) dan CO2, oleh perubahan metamorfik antara fasies sekis hijau ke amfibolit pada T sekitar 400-600°C
Contohnya: greenstone belts → Homstake mine/S-Dakota, USA
DASAR TEORI
TINJAUAN PUSTAKA
Tatanan tektonik pembentukan endapan orogenik yang berada pada batas kontinen, zona akresi atau kolisi (Groves et al, 1998).
MINERALISASI
CASE: BOMBANA
Mineralisasi :•cinnabar (HgS) •stibnit (Sb2S3). •pirit (FeS2)•kalkopirit (CuFeS2) •Goetit (FeO(OH))
ALTERASI HIDROTERMAL
CASE: BOMBANA
Urat kuarsa
Argilitisasi
ArgilitisasiSilisifikasi
Klorit-karbonat
karbonat
klorit
Karbonisasi.
CASE: BOMBANA
SIFAT FISIK-KIMIA FLUIDA ENDAPAN
CO2-rich fluid
Zona keberadaan endapan emas orogenik bombana dengan beberapa endapan orogenik yang terdapat di Western Australia berdasarkan korelasi nilai temperature pembentukan (modifikasi dari Goldfarb, 2005)
Perkiraan zona keberadaan endapan emas orogenik yang ada di Bombana pada model endapan orogenik (modifikasi dari Gebre-Mariam et al., 1995).
CASE: BOMBANA
South African fossil placers (gold-bearing conglomerates)
D. ENDAPAN EMAS PLACER
PLACER GOLD DEPOSIT
2. Perak (Ag)Ditemukan dalam bentuk - Native silver (sebagian besar)- Ag-sulphides.
Native silver di temukan dalam 2 bentuk utama: (1) Zona teroksidasi dari suatu endapan bijih.(2) Endapan larutan hidrotermal (primer).
Ag-sulphides, mineral utamanya: Acanthit (Ag2S) dan aguilarit (Ag4SSe) pada endapan
hidrotermal (low sulphidation epitermal) serta argentit (Ag2S) pada temperatur lebih tinggi.
Ag-sulphides sering bersama-sama ruby silvers seperti pyrargyrit (Ag3SbS3) dan proustit (Ag3AsS3). Juga sebagai inklusi dalam galena argentiferous galena.
Mineragrafi bijih perak dari endapan epitermal Pongkor, Indonesia
Acanthit (Ag2S) sebagai mineral perak minor berasosiasi dengan emas pada endapan sulfida rendah Pongkor, Jawa Barat (Warmada, 2003).
Notes: Gn = galena, Po = Pyrrhotit, Sp = Sphalerit, Uy = Uytenbogaardtit (Ag3AuS2), Mck = Mckinstryit (Ag,Cu)2S, Smy = stromeyerit (AgCuS) and El = Au-Ag alloy ((Au,Ag).
Analisis kimia mineral dari sulfida perak dari Pongkor, Indonesia
1
2
3
4km
MAGMATIC-METEORIC
1
2
3
4km
1
2
3
4km
MAGMATIC
Textures: restricted Textures: diverse, modest Textures: diverse, spectacular
LOW SULFIDATIONHIGH SULFIDATION
Au-Ag-Cu Au-Ag
INTERMEDIATE SULFIDATION
1
2
3
4km
METEORIC
?
Au-Ag, As, Cu, Sb, Bi
Stockwork, Golden Cross
Vein, Golden CrossVein, Hishikari
Vein, La Guitarra
LOW
SULFIDATIO
N
FORM
Chinkuashih La Coipa
Akeshi Sulfide vein, El Indio
HIGH
SULFIDATIO
N
FORM
Characteristic Textures
Neutral-pH, meteoricLow-Sulfidation
banded veins
breccia veins
drusy cavities
crustification
lattice texture
Acid-pH, magmaticHigh-Sulfidation
‘vuggy quartz’
massive quartz
massive sulfide veins
crudely banded veins
White and Hedenquist, 1995
La Guitarra Golden Cross
LOW
SULFIDATIO
N
TEXTURES Dealul Crucii, Baia Mare Aginsky