rock and mineral identification for engineer.pdf

8/11/2019 Rock and Mineral Identification for Engineer.pdf

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Rock and MineralIdentification

for ngineers

November 99

~u s epartmentofTransportationFederal ighway

dministration


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cidbottle

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gr nite

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8 09g n i y i n g l n s


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Rock And MineralIdentificationfor Engineers


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T BLE O CONTENTS

Introduction ................................................................................ 1

Minerals ..................................................................... ................. 2

Rocks ........................................................................................... 6Mineral Identification Procedure ............................................ 8

Rock Identification Procedure ............................................... 22

Engineer ing Properties of Rock Types ................................. 42

Summary ................................................................................... 49

Appendix: References ............................................................. 50

FIGUR S

1. Moh s Hardness Scale ......................................................... 10

2. The Mineral Chert ............................................................... 16

3. The Mineral Quartz ............................................................. 16

4. The Mineral Plagioclase ...................................................... 17

5. The Minerals Orthoclase ..................................................... 17

\6. The Mineral Hornblende .................................................... 18

7. The Mineral Calcite ............................................................. 18

8. The Mineral Muscovite ....................................................... 19

9. The Mineral Biotite .............................................................. 19

10. Mineral Identification Flowchart .................................... 20

11. The Rock Limestone .......................................................... 27

12. The Rock Marble ................................................................ 27

13. The Rock Dolomite ............................................................ 28

14. The Rock Serpent ine ......................................................... 28

15. The Rock Gneiss ................................................................. 29

16. The Rock Schist .................................................................. 29

17. The Rock Grani te ............................................................... 30


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FIGURES cont.)

18. The Rock Syenite ............................................................... 30

19. The Rock Granodiorite ......... ..... ....: .. ................................ 31

20. The Rock Gabbro ................ ........................ .............. ......... 31

21. The Rock Diabase ..... ...... ............ ........ ............................. .. 32

22. The Rock Pyroenite ........................................................... 32

23. The Rock Peridotite ...... ..... ......... .............................. ......... 33

24. The Rock Sandstone .......................................................... 33

25. The Rock Quartzite ............................................................ 34

26. The Rock Conglomerate ................................................... 3427. The Rock Limestone (fine grain) ..................................... 35

28. The Rock Dolomite (fine grain) ....................................... 35

29. The Rock Shale ................................................................... 36

30. The Rock Slate ................ ..................... ...... ........................ .36

31. The Rock Rhyolite ............................................................. 37

32. The Rock Andesite .............. ................ ....... ..... .......... ......... 37

33. The Rock Basalt .................................................................. 38

34. The Rock Basalt (vesicular) .............................................. 38

35. Rock Identification Flowchart, Part A ............................ 39

36. Rock Identification Flowchart, Part B ............................ .40

T BLES

1. Mineral Groups and Their Common Minerals ................. 3

2. Rock Classes and the Common Rock Types ...................... 7

3. Selected Properties of the Common Minerals ................. 11

4. Mineral Identification Procedure ...................................... 14

5. Rock Identification Procedure ........................................... 19


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ntroduction

Civil engineers routinely use rocks as aggregate material intheir construction projects. However, many engineers donot have extensive training in rock and mineral identifica-tion . This guide, which expands on an article and subse-quent publications (Woolf, 1950, 1951, 1960) written for theBureau of Public Roads, can help practicing civil engineersto identify rocks and minerals and to better understandtheir characteristics and performances in certainapplications.

This guide will not turn engineers into geologists orpetrographers, but it can help engineers to make basic

distinctions among various natural rock and mineral types.The guide can also help engineers better understand whycertain types of rocks and minerals have desirable orundesirable characteristics as potential aggregates.

The equipment needed for the procedures in this guide isinexpensive and eas.ily obtained. The samples that are to beidentified are assumed, for our purposes, to be large-sizedcoarse aggregate pieces or hand samples coming directly

from the quarry or gravel pit. To judge the hardness ofvarious minerals, the user will need a pocket knife with agood steel blade and a copper penny. Other useful items area small bottle (with eyedropper) of dilute (O.lN) hydrochlo-ric acid (HC ), a magnifying glass, and a magnet.

To keep the identification process simple, this guideoutlines procedures that rely as much as possible on thevisual appearance of rocks and minerals. Basic tests forhardness and reactivity with dilute hydrochloric acid areincluded for help in classifying a sample.

Those interested in further information may consult the listof references at the back of this manual.

For questions or comments on this manual or the proce-dures discussed, please contact Dr. Stephen W. Forster,Pavements Division, (703) 285-2073.

ock and Minera l Identification


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inerals

Minerals are strictly defined as naturally occurring chemicalelements or compounds formed as a product of inorganicprocesses (Hurlbut, 1963). Rocks are composed of an assem-blage of one or more distinct minerals. This definition of

minerals excludes shells, coral, and other organically formedmatter which nonetheless are important constituents of somelimestones. For the purposes of this guide, these componentsare also considered to be minerals.

Mineral Types . Minerals can be separated into groups on thebasis of chemical composition. Although incomplete, thefollowing list of groups includes those minerals which wouldnormally be encountered by a practicing engineer. These

groups, including their common minerals, are shown in tablel

Elements. This group consists of chemical elements thatoccur in nature in an uncombined state. Examples aresulfur, graphite, and gold.

Sulfides. Included in this group are combinations ofvarious metallic elements with sulfur. An example is pyrite.

Oxides . The minerals in this group contain a metal elementin combination with oxygen. The iron mineral hematite isan example. A subgroup within the oxides is the hydrox-ides, which include oxygen in the form of the hydroxylradical or water. Limonite is an example of a hydroxide.

Halides. Halides are naturally occurring chlorides,fluorides, bromides, and iodides. Examples are halite(rock salt) and fluorite.

Carbonates. The carbonate group of minerals contains thecarbonate radical. The common minerals calcite anddolomite are included here.

Phosphates . Minerals whose composition includes thephosphate radical are included in this group. One exampleis apatite.

Sulfates. These minerals include the sulfate radical.Gypsum is an example of a common sulfate mineral.

Silicates. Silicates form the largest group of minerals. Theycontain various elements in combination with silicon andoxygen. Examples are quartz and feldspar.

Although there are literally hundreds of minerals, a practicing

engineer really only needs to be familiar with and be able toidentify about twenty. To classify an aggregate sample as agiven rock type, it is usually necessary to identify only its twoto three main mineral components.

Rock and Mineral Identification


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Table 1 Mineral Groups and thei r ommon Minerals

Group Minerals omments

E le ment s sul fur M ay e see n as tr aceg raphit e min e ra ls in so me roc ks.go ld

s ilve rco pp e riron

S ul f ides PYRI TE , iron di sulfid e Co mm on accesso ry min er a lin a ll 3 roc k classes.

ga lena , lead s ul f ide So urce of lead.

sph a le rit e , z inc s ul fide So ur ce of zi nc .

Ox ides H E M ATI TE , fe rri c ox ide Co mm on min e ra l in a ll 3roc k types; so ur ce of rust-red co lo r in many roc ks.

M AG N ETIT E, fe rrous M ag ne tic; co mm onox ide accessory min e ra l in a ll 3

roc k classes.

LIMO N IT E , hyd ro us iro n Ye llow- brow n ; fo rm ed b yoxide a lte rin g of o the r iro n

min era ls.

Ha lides ha lite , s od ium chl o rid e Co mm on roc k sa lt .

FLOU RIT E, ca lci um Co mm on accesso ry min era l.f10 urid e

Ca rbo nates CA LC IT E, ca lcium O ne o f th e co mm onca r bona te min era ls ; m ajo r co mp o ne nt

of lim es tone .

DO LO MI TE , ca lc ium Co mm on min e ra l; m ainmag nesi um ca rb ona te min e ra l in the rock do lomit e

(a lso ca lled d o los to ne .)

Ph ospha tcs A PATI TE, calc ium Wid c ly di str ibut cd acces-(f1uo ro- , chl oro-) ph os ph a te so ry m ine ra l in th e 3 roc k

cl asses.

S ul fa tes G YP SU M , hydr o us ca lc iu m Co mm on min e ra l,sul f ate es pec ia lly in lim es tone a nd

sha le.

ba rit e, ba rium sulfat e Co mm on accesso rymin e ra l, es pec ia lly in

se dim e nt ary roc ks .

No te: Th ose min era ls listed in capit a l le tters a re mos t lik ely to be e ncoun t ered .

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Table 1 Mineral Groups and their ommon Minerals

Group Minerals omments

Sili ca tes QUART Z, s ilico n di ox ide

C HERT , s ilico n dioxide

F E LDSP A RS:

OR T HO C LA S E,po tas ium aluminum

sili ca tePLAG IOC LA S E,so dium /ca lc iuma luminum s ilica te

OLIVIN E , mag nes ium / ironsili ca te

GA RN ET , ca lc ium , iro n,m ag nes ium. m angan ese/a luminum , tita nium , iron ,c hr om ium sili ca te

z irco n , z irco nium s ilicate

PYROX ENES , magn e sium ,iron , ca lc ium , so dium ,lithium /m ag nes ium , iron,aluminum sili ca te

AMPHIB O LES , m ag ne-s ium , iro n , ca lcium ,so dium /mag nes ium , iron ,a luminu m s ilica te

On e of the co mmonmin e ra ls ; ha rd and ve ryres ista nt t o c he mi cal andphy sica l b re a kd own .

C rypt oc rys ta llin e ( mi c ro -sco pic c rys ta l s ize) va rie tyo f qu art z.

Famil y of min e ra ls c ommonin a ll 3 roc k c lasses.

Ve ry co mm on min e ral.

Inc lud es a se ries withco mp os iti ons ran g ing fromthe so d ium end-m e mb e r(a lbit e) to the ca lc ium e nd-me mb e r (a no rthit e); th esemin e ra ls a re ve ry co mmon .

Fa irl y co mm o n; m os t of tenin d a rk e r igneo us ro cks.

Co mm on accesso ry min e ra lin m any ig neo us roc ks; ma ya lso occ ur in the 2 o th e rroc k cl asses.

Co mm on accesso ry min e ral.

Co mm on in many igneou sro c ks; a famil y o f min e ral s.

Co mm on in m any igneou sroc ks ; a famil y o f min e ra lsth a t includ es HORN -BL E ND E.

N ote: Those min eral s lis ted in capita l letters ar e mo st lik ely to be encount ered.

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Table 1 Mineral Groups and their ommon Minerals

Group i Minerals i omments

Sili ca tes (co nt. ) CLAY MINERAL S:

K AO LI NITE, hyd ro usa luminum silica te

talc , hydr ous m ag ne-sium silica te

SERP EN TI NE , hydr o usmag nes ium s ili ca te

MI CA MINE RALS:M USCOVI TE, hydro uspotas ium aluminumsili ca te

BI OTI TE , hydro uspotas ium , mag nes ium /iron , a luminum sili ca te

CHLORIT E, hyd rousmag nes ium / iron a lumi-

num silica te

A group of usually fin e-g rai ned so ft min e ra ls.

Co mm on c lay min era l inso il and se dim entary roc ksth at includ es montm o rill o-nit e .

Co mm on in m etamorphi croc ks.

Co mm on min e ra l inmetamorphi c roc ks.

Ve ry co mm on min era l inmetamorphi c a nd i gneo usroc ks.

Ve ry co mm on min era l inm etamorphi c a nd i gneo usroc ks.

Co mm on min e ra l inmetamorphi c roc ks.

No te: Tho se min era ls listed in capital letters a re mo st likely to be encount ered.

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Ta ble 2 Rock Clas ses and the Common Rock Types

Class Rock Type Comments

Igneo us Form ed from molt en rock.

subcl ass Ex tru s ive Fin e g rain ed.

fe lsite G enera l n ame whi chinclud es the rocks: rhy o lite;tra chyte; latit e ; and es ite.

basa lt Da rk co lo r.o bs idi an Gl assy.pumi ce Fro th y; light we ight.

sub class Intru sive Medium t o co ur se-g ra ined.granit esye ni teg ranodi o ritemonzo nit edi o rite

ga bbr o G abbro and di abase havedi abase the sa m e co mp os ition ;

g rabb o is co urse g ra ined ,di aba se is medium g ra ined .

py roxe nitepe ri do tit e

Se dim ent ary lim es tone Form ed b y parti c ledo los tone (do lomit e) de pos iti on or chemi ca lsa nd stone prec ipit ation .shalec hertco ng lom erate

Metam orphi c s late Fo rm ed b y high h ea t and /o rsc hi st pr ess ure ac tin g o n ex istin ggne iss roc k .qu a rtz ite

marbl edo lomiti c m arbl ese rpentinit e

o ck a nd M iner a l d en tif ica t ion _


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Mineral Identification Procedure

Sin ce mineral s are the compon ent s of roc ks, th eir id entifi ca -tion is a n int egr al part of pr oper r ock id enti ficati on . For thi sid enti fica tion pr oce dur e, thr ee characteris tics of min eralsw ill b e of m ajor import ance: hardn ess , reac tivity w ith dilut ehyd roc hloric acid , and cleavage .

Hardnes s

Figur e 1 is a gra ph of th e Mo hs hardn ess scale a ppli ed tomin erals. Also s hown o n th e gra ph is the re lative hardn essof seve ral comm on it ems that can b e used to se parat e th emin erals. The knife blad e is parti cularl y useful in separatin gthe comm on h ard er min erals (qu artz a nd th e feldspars)

from th e comm on so fter min erals (calcite and d olomit e) . Totes t fo r h ar dn ess wi th any of th ese items, two a ppr oac hesmay be used :

Use the knife b lade (or copp er p enn y, etc.) as a too l toattempt to scra tch the min eral

Use the mineral to a ttempt to scra tch the tes tin gmaterial.

Doing i t both ways w ill often give a cle ar er in di cati on of th ere la tive hard ness of the two materials being comp ared .

eI Reactivit y

This test se rves to d iffe rentia te the car bonate min erals(which r eact w ith H e\) from oth er m ineral types. Th e acidused i s dilute He l. The dilut e ac id is obtain ed by mixingwa ter w ith f u ll-s trength aci d . By notin g th e normalit y o f theacid b eing dilut ed, an appropriat e vo lum e of wa ter can b eused to reach the targe t of O I N. Fo r in stance, if the o riginalacid is 1.0N, inc reas ing th e vo lum e of wa ter tenfo ld w illresult in a O.1N. When dilutin g, always add the acid to thewater to avoid splashing fu ll strength acid

Cleavage . f a min eral br ea ks so i t yield s definit e planesur faces, th e min eral is sa id t o possess cleavage. A min eralcan p ossess o ne or m ore dir ections of cleavage , or n one:

The mi cas (e .g. mu scov ite and bi otite) are exampl es ofminera ls wi th di sti nct cleav age i n one di rec tion.

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All the feldspars have two cleavage directions, which areat almost right angles .

Quartz has no cleavage . This fact helps in the distinctionbetween quartz and the feldspars. When quartz and chertare broken , the resulting surfaces often have a typical

concave shape called conchoidal fracture because of itsshell-like appearance. While not a cleavage, this distinc-tive fracture habit can be useful in identification .

Other Characteristics. Some minerals have a distinct,definitive color. However, because the color of mostminerals can vary significantly, color should normally beused as supportive rather than primary evidence. Anotheruseful characteristic is a mineral's ability to transmit light.Depending on the composition, crystallography, and otherfactors, a mineral may be tran parent translucent or opaque.

Table 3 lists the hardness , dilute HCl reactivity, cleavage,and other characteristics of common minerals listed intable 1.

See Table 4 for step-by-step mineral identification proce-dures . The figure references within the table are to photo-

graphs of the more common minerals.

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Figure 1 - Relative Hardness of Minerals in Mohs Scalenumbers in parentheses .

- Diam ond (10)

file

wi ndow s s \ - Co rundum (9)km fe \ - To paz (8)

penn y \ _ Qu artz (7)

fin ger \ - .o rth oclase (6)nail Apa tIte (5)

\

- Flu or ite (4)- Calc ite (3)

- Gy psum (2)

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Table 3 Selected Properties of the ommon M ineralsMineral ardness Cleavage Other

Pyrite 6 - 6 1/2 No ne Br assy; foo l s go ld ; wea the rseas ily to g ive iro n sta in ;co mm on accesso ry min era l inman y roc k t ypes.

Hem atite 5 1/2 - 6 1/2 No ne ( in Red-b row n; co mm on accesso rym ass ive fo rm ) in many ro cks; ce me nt in many

sand stones.

Ma gne tit e 6 No ne ( in Bl ac k; m ag ne tic; co mm ongranular fo rm ) accesso ry min e ral in many roc k

types.

Lim o nit e 5 - 5 1/2 No ne Ye llow -bro wn; ea rth y; mayapp ea r so ft er th an 5; for med b ya lte ration of othe r iron min eral s.

Fluorite 4 I pl ane Co mm on accesso ry min era l inlim es tone s and d o los tones;trans luce nt to transparent.

Ca lc ite 3 3 pl anes a t 75 0 Very co mm o n; occ ur s in manyroc k t ypes ; chie f min era l inlim es tone ; v igo ro us reac tionw ith dilut e HC .

Do lomit e 3 1/2 - 4 3 pl anes a t 74 0 Co mmon ; with ca lc ite indo lomiti c lim es tone o r d o los tone

(>50 % do lomit e) ; v igo ro usreac tio n with dilut e HC I yw he n p owd ered.

Ap atit e 5 I pl ane, poo r Co mm o n min or accesso rymin e ral in a ll roc k c lasses.

Gy psum 2 4 plan es ; Co mm on min e ra l, es pec iall y inI pe rfec t lim es tones a nd shales ; m ay

occ ur in laye rs.

Qu art z 7 No ne Very co mm on; m ay occ ur inmany rock types; g lassy ;trans luce nt t o tra nspar ent ; maybe co lo red ; ve ry res istant t owe ath e rin g; c hie f min eral insa nd ston es.

C hert 7 No ne C ryptoc rysta llin e ( micro sco piccrystal s) va riety of qu a rtz;app ea r s mas s ive to nake d eye;comm o n in lim es tones or inco mpl ete laye rs assoc iated withlim es tones ; light t an t o lightbro w n; s imil ar min e ra ls: flint(dark b row n to bl ac k); j as pe r(red ); chalcedo ny ( waxy loo k,tan t o br ow n).

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Table 3 Selected Properties of the Common inerals

ineral Hardness Cleavage Other

Ort hoclase 6 2 p lanes A fe ldspar; very common i nat 90 many roc k t ypes; w hite to grey

to red -p ink; trans lucent to

trans pare nt ; cleavage sepa rates itfro m qu artz .

Pl ag ioc lase 6 2 planes A fe lds par; very co mm on inat 94 many roc k types; a ppea rs s im ilar

to ort hoclase - dist ingui shed bythe prese nce of thi n, para lle llines o n cl eavage faces d ue tocrys ta l stru ctur e .

Oli v ine 6 1/2 - 7 No ne Tr ansparent to t ransluce nt ; o livegree n; g lassy; co mm on

accessory min eral in the dar kerigneo us rocks .

Ga m et 6 1/2 - 7 1/2 No ne Red t o red-brow n; transluce nt totransparent ; co mm on accessorymin era l in m etamo rhi c a nd so meigneo us roc ks; a lso in sa nds a ndsand stones.

Zirco n 7 1/2 No ne Us ually co lorless to brow n;us ua lly transluce nt ; co mm onaccesso ry min eral in igneo usroc ks a nd so me metamorphi crocks; a lso in sand s a ndsa nd stones .

Pyroxe ne 5 7 2 planes Most co mm on in the darke r(min eral gro up) at 87 igneo us roc ks; usua lly g ree n t o

and 93 blac k; t ransluce nt t o trans parent ;'mos t co mm on min eral: augite.

Am phib ole 5 6 2 planes Mos t co mm on in metamorp hic(min era l gro up ) at 5 6 roc ks a nd the darker i gneo us

and 124 rocks; usually dark gree n tobrow n t o black; t ransluce nt t otransparen t; mos t co mm onmin era l: horn blende; di stin -guished fro m p yroxe nes bycleavage.

C lay 2 - 2 1/2 1 plane Us ua lly f ine gra ined; eart hy;M inera ls of ten d e rive d f rom wea the rin g(a gro up ) of fe ldspa rs; mo ntmori llonit e is

the swe llin g c lay t hat ex pandswith the a bso rpti on of wate r;

illit e is the co mmo n clay m inera lin m any s hales.

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Table 3 Selected Properties of the Common M inerals

ineral Hardness leavage Other

Talc 1 plan e Ve ry soft , greasy; cleavage maybe hard to see beca use of fine nessof parti cles; co mm only w hit e to

pale gree n; usually in metamor-phi c o r a ltered i gneo us roc ks.

Se rpentin e 2 - 5 no ne Mass ive to fi brous; greasy to(usually 4) waxy ; var ious shades of green ;

found i n a ltered igneo us o rmetamorph ic rocks; f ibro usva rie ty is the so urce of as bestos.

Mu scov ite 2 - 2 1/2 plane A m ica ; perfec t cl eavage a llowssplitt ing into t hin , clea r tr anspar-ent shee ts; usua lly light ye llow to

light brow n ; co mm on in lightco lored igneo us rocks a ndmetam orphi c rocks.

Biot ite 2 1/2 - 3 plane A mica; perfec t cl eavage a llowssplittin g int o t hin smokytranspare nt shee ts; usually da rkgree n t o brow n t o blac k; fo un d inlight to medium co lored igneo usrocks and m etamorphi c rocks .

Chlori te 2 - 2/12 plane Simil ar to the m icas ; usuallyocc urs in sma ll part icles socleavage produ ces flake; flakesare flex ibl e but n ot e las tic as arethe mi cas ; usually so me shade ofgree n.

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Table 4 Mineral Identif icat ion Procedure

Is it h arder than a knife?I f YES, what is its overall appearance?

A. Dull and ea rt h y, waxy, o r m e ta llic.

1. Ma g ne tic (s m all frag m ent s s tick to th e kn ife bl ad e)- magnetite.

2. No nm ag n e tic, how d oes it br eak (frac tu r e)?

a . Shar p ed ges; co nch o idal (co n cave, lik e th e in sid e ofa n oys ter shell) s ur face - chert (figur e 2).

b. Rou gh, un eve n surfa cered-br own to bl ac k - hematite ;br o w n t o d ark b ro w n - limonite .

NO TE: both hematite and limonite can appear softer than aknife if not t ted on a fresh unweathered surface

c. Pa le to m edium br ass co lor, o ften in cubi c c rys ta ls- pyrite.

B. Vitr eo u s (g lassy), tr ansp a re nt to tr an slu ce nt.

1. No cle avage.

a. Co lo rless to w hit e to p ale pink - quartz (figur e 3).

b . O live gree n - olivine .c. Red-b ro w n - garnet.

2. Two clea vage pl anes , in t erse ctin g a t a ppr oxi m a tely a90-d eg ree a ngle .

a. Goo d t o perfec t cl eavage su rfaces(feld sp a r g roup , o ne s urfa ce w ith p a rall el s tri a tions)- plagioclase (figur e 4); n o s tri a tion s pr ese nt- orthoclase (fig ur e 5) .

b . Poo r to fa ir cleavage surf aces - pyroxene.

c. Two cleavage pl an es , in t ersec tin g a t 120 a nd 60d eg rees - amphibole (includ es hornblende )(fi gur e 6) .



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Table 4 Mineral Iden t ification Procedure cont.)

II f NO, will it scratch a copper penny?A. f ye s, will it react with dilute HCl ?

1. v igorou s reaction - calcite (figure 7).2. minor reaction when whole, vigorou s wh en powdered

- dolomite.

3. no reaction .

a. One plane of perfect cleavage - fluorite.

b. plan e of poor cleavage - apatite .

c. Non-crystalline ; waxy to grea sy or fibrou s appearance

- serpentine .B. f no, do es it hav e perfect cleavage which allow s s plitting into

thin sheet s?

1. Yes - mica group.

a. Pale , light color s, sheet s ar e flex ible and ela stic- muscovite (figure 8 .Usually in very small flakes ; sheets ar e flexible butnot ela stic - chlorite.

b. Dark colors , green to brown to black - bi otite(figure 9) .

2. No .

a. Opaque , very fine grained - clay minerals.

b. Translucent to transparent - gypsum.

NOTE: Color has been used in the latter s ges of some decisions despite the cautiongiven on the use of color In the instances where color is used, its use is judgedappropriat e for the minerals involved and the low likelihood of encounteringexamples outside the color ran ges given. Figure 1 is a d ecision tree diagram ofthe outline g iven above

Two copie s of thi s diagram are al so included on weatherproof cards ofpocket si ze for handy reference in the field.



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hotos

Figure 2 The Mineral hert

Figure 3 The Mineral Quartz

6 Rock and Mineral Identification


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Figure 4. The Mineral Plagioclase (note striations due to crystal structure)

Figure 5 . The Mineral Orthoclase (pinkish-tan) and Quartz (white)



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hotos

Figure 6 The Mineral ornblende

Figure 7 The Mineral Calcite



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hotos

Figure 8 . The Mineral Muscovite

m

Figure 9 . The Mineral Biotite



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Figure 10 Mineral Identification Flowchart Part B Not Scratched y a Knife


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Rock Identification rocedure

Id entifi cation of rock typ es involves not only identi fy ing theirmin eral constitu ents a nd th eir r ela tive am ount s, but also ase ries of charac teristics of th e roc k. The thr ee classes of roc ks,

igneo us, sedim en tary, a nd metamorphi c, we re definedearlier. Because rocks fro m diff erent classes can app ea r quit esimil ar, and rocks w ithin th e sa m e class can often app ea rqu ite diff erent , se para tion b y class w ill not be a specific partof the identifi ca tion p rocess.

See table 5 for step-b y-step rock id entifi ca tion proce dur es.Refe r t o the min eral id entifi ca tion p roce du r e in t able 3 asnecessary to s upport some porti ons of this p roce dur e.

The roc k id entifi ca tion p roce du r e in t able 5 result s in th edistinction of 26 rock types . Thi s degree of se parati on isposs ibl e und er m ost circum stances. Howeve r, if a sa mpl e isnot very big, or small to medium min eral gra in size makesdefinit e identifi ca tion diffi cult , identifi cation to the nex t-to-las t leve l of the o utlin e w ill often suffi ce for pr elimin aryengineerin g purp oses . Thi s leve l of id entifi ca tion i s o ftenadequ ate, because the e ngineerin g properties of the roc k

types w ithin one ca tegory a t thi s level are usually verysimil ar.

One exa mpl e o f such a ca tegory is given in th e proce dur e: thefelsites. This term includ es a ll the fine-grained , light-coloredigneous roc ks. These a re all comp ose d pr edomin antl y o ffe ldspar, e ither orth oclase o r pl ag ioclase, w ith or w ith outlesse r amount s of qu artz plu s so me accessory min erals.Because of the similarity of composition and texture withinthe felsite group, the behavior when used as a constructionmaterial of all the rock types in the group is very similar .

The coarse -grained equi va lents of th e felsi tes may be trea tedsimil arly. This category includ es g ranite, gra nodiorite,sye nite, m onzo nit e, and di orite. Since qu artz is a min eral th atis eas ily recog nized w ith a littl e pr ac tice, separating those thathave qu artz (granit e a nd gra nodi orite) from th ose that d on' t(sye nit e, m onzo nit e, and diorite) is rela tively easy. F urth erca tego riza tion of these two gro up s depend s o n th e rela tiveam ount s of the two feldspar min era ls, or th oclase a ndplag ioclase .

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Table 5 Rock Identification Procedure

I. Distinct mineral grain s, ea sily seen b y the naked e ye.A. Entir e rock surf ace eas ily scrat ched b y a kni fe . (Make sur e that th e

miner al surf aces a re being sc ratched , and n ot simpl y that p oorl ycemented grains a re being di slodged .)

1. Reactivity with dilut e Her.a. Vigo rou sly, with much effer vesce nce - limestone or

marble (figur es 11 and 12).

N OTE: If visibly crystalline with interlocking g rains, the rockin question may be a marble or a limes tone. Withou t largersamples to reveal the presence or absence of cha ra cteristicirregular band ing ( marbled appearan ce) and other texturalfeatu res, distinction between the two may not be possible. Thepresence of 0ninterlocking minera l gra ins and und istortedfossils confirm the rock is a limeston e (figure 11).

b. Slow ly o n th e rock surface , v igorou sly if th e rock i spowd ered - dolomite (dolostone ) or dolomitic marble(figur e 13) .

NOT E: the note g iven for l.a . above, app lies here also.

c. No reac tion, greasy or waxy a pp ea rance - serpentinite

(figur e 14).B. Entir e rock sur face cann ot be scratch ed b y a knif e, (that i s, so me or

all of th e min erals pr ese nt are hard er th an th e knif e blad e).

1. The min erals a re int ergrown (contact surfa ces betw ee nmin eral s ar e irreg ular and interlo cking) .

a. Min eral s a rran ged in l ayers or b and s (foliat ed) .

1 Irr egul ar, coa rse foliation if poo rly deve loped (orlinea tion), with zon es of light min erals (often quart zor f eldspar, or b oth ) alt ernatin g with zones of darkmin erals (often biotit e or hornbl end e) . Th e folia tion i snot d eve loped to the ex tent th at plan es o f we akn essare pr ese nt in the rock - gneiss (figur e 15) .

(2) Min erals a rranged in thinn er, more di stin ct layerswhich create plan es of weakn ess along which th e rockma y be split. Mica mineral s ar e plentiful - schist(figur e 16).

NOTE: Some sandstones are color banded. However,examination of the minera l g ra ins w ill show a lack ofintergrowth .

Rock and Mineral dentification 3


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Table 5 . Rock Identification Procedure cont .)

easily be separa ted from the other rocks listed under B.1.b becau se theonly mineral present in significant amounts is quartz.

c. Gr ave l-sized p articl es of rock s and min eral s, cement ed b ysilica, clay, calcit e o r hematit e - conglomerate

(figur e 26).II. Very fine miner al grains, not visible to the nak ed eye.

A. Gla ssy.

1. Loo ks like g lass; may have a few inclu sions or bubbl es; d arkbro wn t o bla ck - obsidian.

2. Contain s many bubbl es, froth y - pumice.

B. Dull , ea rth y or stony.

1. Can b e scratched w ith a knif e.a. Reacts v igorously w ith dilut e HCl - limestone

(figur e 27).

b. Reacts s low ly w hen whole o r vigo rously w hen p ow d eredwith dilute H CI - dolomite (figur e 28).

c. Reacts s lowly or n ot at all w ith dilut e HCl, w hether whol eor p owder ed .

(1) Tend s to break int o flaky pieces - shale (figur e 29).

(2) Laye red ; br eaks int o thin , flat shee ts - slate(figure 30).

2. Can' t be scratch ed with a knife .

a. Very hard; fractur ed surfac e is smooth (ma y be conchoi -dal) with sharp ed ges ; surfa ce may app ea r wa xy; tan t oblack color - chert .

b. Mass ive; dull- app ea rin g fra ctur ed surfa ce; may ha ve s mall

inclu sion s of gla ss or crys tal s.(1) Light t o medium color s - felsite .

NOTE: Felsite includes the extrus ive igneous rock types:rhyolite figure 31 , trachyt e, latit e, and and esite figure32) which u sua lly can t be distingu ished by the naked eye. Theydiffer bas ically only in the relative amounts of the two feldspars(their p rima ry constituents) and the presence or absence ofquartz.

(2) Dark t o bla ck color - basalt (figure s 33 and 34) .



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Beca use thi s ra tio betwee n orth oclase a nd pl ag ioclase is acontinuum , roc ks m ay be found on th e bord erline betwee nth e two gro up s. f in d oubt , class ifying a rock as a g ranit e /granodi orit e o r sye nite/ monzo nit e is suff icie nt b eca use ofth eir sim ilar p erform ance in constru ction . As the percent age

of plag ioclase i n thi s fa mil y of rocks increases , the perce nt -age of so-called d ark min erals (mainl y a mphib oles a ndpyroxe nes) also inc reases, g ivin g the roc k a dar ker ove rallap pea rance. This of ten allows th e di stin ction of di orit efro m th e o th er m emb ers of th e g roup .

The two dark i gneous roc ks - p yroxe nit e a nd p erid ot ite -may be ind istin gui shable in h and specime n if th e min eralcrys tal size is too s mall to di sting uish cleavage. As was th e

case above, id enti fy ing a roc k as bein g o ne of th e memb ersof thi s continuum i s helpful since they behave s imil arly inconstru ction u ses.

Alth ough of ten eve n-t ex tur ed (min eral gra ins a re a ll aboutthe sa m e sizc) , all igneous roc ks m ay exhibit w ha t is calledporp hyriti c tex tur e. A por ph yriti c tex tur e is defin ed as o ne

in w hich one or mo re min era ls occur in crys tals mu ch large rthan th e sur ro undin g min eral s in th e rock. t is the s izedi ffe rence ra th er th an abso lut e s ize w hi ch de fines thetex tur e. Th erefo re it can ex ist as 1 mm crys tals di spersedth rough a basa lt or 10 mm crys tals in a g ranit e. Thepresence of thi s texture does not affect the rock's clas sifi-cation, although it may affect some of its engineeringproperties, which will be di scussed here.

Figur es 35 and 36 are two decision tr ee di ag rams of th eoutlin e give n above. Th ey a re a lso includ ed on th e wea ther-p roof ca rd for use in the field .

6 ock and Mineral dentif ication


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hotos

Figure 11. The Rock limestone (coarse grained example)

Figure 12. The Rock Marble (note banding)



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hotos

Figure 15. The Rock Gneiss (note foliation of minerals)

Figure 16 . The Rock Schist (note distinct foliation of minerals)



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ho tos

Figure 17 The Rock ranite

Figure 18 The Rock Syenite



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hotos

Figure 19 The Rock ranodiorite

Figure 20 The Rock abbro



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Photos

Figure 21 . The Rock Diabase

Figure 22. The Rock Pyroxenite



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Photos

]

Figure 23 . The Rock Peridotite

Figure 24 . The Rock Sandstone (note sandy , grainy appearance)

Rock and Mineral Identificat ion


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hotos

Figure 25 . The Rock Quartzite (note more glassy , sharper surface than sandstone)

Figure 26 . The Rock Conglomerate



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Photos

1 m

Figure 27 The Rock limestone fine grained example)

Figure 28 The Rock Dolomite dolostone) very fine grained example)



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Photo

Figure 29 . The Rock Shale

Figure 30 . The Rock Slate (note thin layers that can be split apart)



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hotos

Figure 31 The Rock Rhyolite

Figure 32 The Rock Andesite



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Photos

Figure 33 . The Rock Basalt

Figure 34 . The Rock Basalt (vesicular)



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Figure 35 - Rock Identification FlowchartRocks with Mineral Grains/Crystals Easily Visible to the Naked Eye

noneS RP NTINIT

Part -A


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Figur e 6 Rock Identification Flowchart Part 8Rocks With Very Fine M ineral Grains / CrystalsNot Easily Visible to the Naked Eye



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Rol e of A ggr egate Source in Identification A na tur alagg rega te may come fro m a sa nd a nd grave l d eposit orfro m a q uarry in th e fo rm of cru shed s tone. For twoimp ortant r easo ns, ident ifyi ng the roc k t ype(s) in a cr ushed

stone is usua lly eas ier th an id enti fy ing those i n a grave lsour ce . First, a cr ushed stone is normally com pose d of onlyone or two close ly related r ock types, eve n th ough somechanges in min era logy a nd tex tur e may occur wi th ve rti calor h orizo nt al separa tion, or both, in th e q uarr y. Seco nd ,since it is a c ru shed m aterial, sa mpl e sur faces are f reshlybroken and clea n, w h ich is the id ea l condit ion for id enti fy-ing min erals a nd deter minin g tex tur e.

A sa nd and grave l sour ce, on th e o th er h and , has seve ralpotenti al di fficulti es for rock a nd min era l id entifi ca tion.Sin ce sa nd and grave l are wa ter tr anspo rted and deposited,rock f rag ment s contained th erein can h ave many d iffere ntoriginal bedroc k sour ces . As a result , a s ingle g rave l d epositcan cont ain m any, often unr elated , rock types. Sampl esm us t th ere fore be take n especially care full y to ensur e th atthey a re repr ese ntative o f th e w hole deposi t. n add ition,

par ticl es in a sa nd and grave l d epos it are often wo rn orcoa ted wi th seco nd ary min era ls or both , mak in g id en tifica-tion of th e min era ls more diffi cult. Thi s can often b e

i by we ttin g the particl es before exa min a tion or bybr eaki ng the parti cles to expose a fresh sur face.

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Engineering Properties of ock Types

Alth ough th ere can b e so me va ria tion in enginee rin gpropert ies w ithin a g iven r ock t ype, know ing roc k ty pe oreve n roc k class fo r th e agg rega te w ill often p rov id e insightabout its ph ys ical, mechanica l, and / or chemica l p ropert ies.

Th ese ge neral re la tionship s betwee n roc k type a nd p roper-ties can h elp in selec tin g a p roper agg rega te ma terial for agiven appli ca tion. ASTM C -294 "Stand ard D esc ripti veNo menclatur e for Co nstitu ent s o f Na tural Mineral Aggre -ga tes" a nd STP 9 B on t es ts a nd pr operties of concretemakin g materials (ASTM, 1986a, 1978) provi de a dditi onalin form ation on thi s subj ect. Va rious engin ee ring proper tiesare di scusse d b elow.

Absorption . Absorpti on is close ly related to t he poro:. ity(pore space) in th e roc k and it s perm eabilit y (abilit y totransmit wa ter). Sedim entary rocks (w hich in ge nera l arecomp ose d of ind ividu al rock frag ment s or minera l grains,or both , packed to va rying deg rees) tend t o have mor tspace betwee n grai ns a nd th erefore higher a bsorpt ion th anigneo us a nd m etamorph ic roc ks. The pore s pace in i gneo usand metamor ph ic roc ks is ge nera lly less d ue to a n interlock-ing g rain stru ctur e crea ted by the mi neral crys tallization (orrec rys talliza tion) in pl ace.

Base d on t es ts condu cted on th ousa nds of agg rega tesa mpl es fro m across the countr y by th e FHW A's fore run-ner, th e Bur ea u of Publi c Road s, absorp tion of sedi mentaryroc ks was found to be in th e 1 to 2 percen t ra nge, w hileigneous a nd m etamorph ic roc ks were usually we ll below 1

perce nt (Woolf, 1953) . Of the se dim ent ary rocks , sa nd sto neand c hert tend ed to be on the high e nd of the ra nge, a ndlimes tone a nd d olomit e at the lower e nd . Keep in mi nd th atw hile these tren ds a re useful, th ese va lues are ave rageresult s, and a s pecific roc k sour ce can be sig n ificantl y aboveor below these leve ls.

FreezelThaw Durability and D-Cracking . The ability of a nagg rega te to w ithstand th e rigo rs of f reeze/thaw (FITcyclin g in th e prese nce of moistur e of ten h as a compl exrelationship wi th it s poros ity a nd p erm eability . Rocks canhave fairly high a bsorpti on and still b e dur ab le und er F /Tconditi ons if their pe rm eabili ty is such th at any wa ter

4 c k nd Mineral dentification


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present within the rock can migrate as freezing takes placeto accommodate the volume change. Many sedimentaryrocks fit this description . Igneous and metamorphic rocks,on the other hand, are durable under IT conditionsbecause their absorption is typically low.

F T durability tends to be lower for rocks having certaincombinations of porosity, pore size distribution, andpermeability. These rocks can absorb critical amounts ofwater over long periods. However, the water cannot escaperapidly enough during freezing, and the pressure buildupdue to the water migration and expansion fractures theaggregate. Certain carbonate rocks found in the CentralUnited States are particularly susceptible to this

phenomenon.

When an aggregate is used in concrete, its effect on the IT

durability of the paste must also be considered. Thenondurable rock described above, when used in concrete,not only cracks itself but may form cracks in the surround-ing concrete . In slabs on grade, these cracks are typicallyseen at the surface as a series of cracks parallel to each otherand a free edge or joint in the concrete. This is the phenom-enon known as D-cracking.

As noted above, rocks with high absorption are durable inan unbound condition, because their permeability allowsinternal pressures to be relieved to their outside as waterfreezing takes place. When these same rocks are enclosed inconcrete, water in the aggregate may develop disruptiveforces when the aggregate is frozen in a critically saturated

condition . This is because the lower permeability of theconcrete paste may not be able to accommodate (at a ratesufficient to prevent pressure buildup) the water beingforced from the aggregate due to expansion during freez-ing. The resulting pressure may be sufficient to cause tensilecracking in the concrete paste (or "popouts" if the aggregateparticle is near the surface). For these IT related distressesto occur, it is assumed that the aggregate is either

0 critically saturated (that is, there is enough waterin the pores so the remaining pore space will notaccommodate the expansion due to freezing) or

ock and Mine ral dentification 4


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(2) it h as a po re sys tem th at w ill not allow a ra pidenough mi gration of wa ter d ur ing freezi ng to preve ntthe bu ild u p of d est ru ctive tensile s tresses.

Wear and Poli sh Re sistance . The wea r and polish res is-tance of a n agg rega te expose d to traff ic a t the pave men tsurface is highly related to th e absolut e a nd r ela tivehardn ess o f th e min erals makin g up the aggrega te. Thesecharacteris tics are es pecia lly criti ca l for the coa rse agg rega tewhen it is to be used in an asph alt p ave men t. Agg rega tescom pose d of soft minerals (comm on ones are calc ite a nddolomi te) or agg rega tes w hose min eral grains are wea klycement ed toge ther w ill qui ckly wea r away (low -wearresistance), leav ing littl e o r n o agg rega te pro trudin g a bove

the ge nera l sur face of th e pave ment. With out thi s prot rud -ing aggrega te, the pave ment h as no dr ainage c hann els forwa ter t o esca pe from b enea th vehicl e tires du r ing rai n, andtherefo re high-speed skid r esistance tend s to be low .

The o ther imp or tant as pec t of skid r es istance to w hich th eaggrega te contribut es is tire a dh esion t o the surf ace . Thepave ment sur face tex tur e necessa ry fo r thi s adh esion ispr ov ided b y t he expose d fine agg rega te a nd th e small sca le(less than O.5mm ) surface tex tur e of th e expose d coa rseagg rega te. To be e ffective, a coa rse agg rega te mu st n ot onlyhave thi s tex tur e initi ally, but also be o f a comp ositionw hich r es ists the smoo thin g or polishin g of th is tex tur eund er tr affic. Pur e lim es tone coa rse agg rega tes may havethi s tex tur e a fter cru shin g, but since the so ft min era ls ofw hich th ey a re comp ose d are eas ily polished , these agg re-ga tes w ill n ot m aint ain thi s tex tur e ve ry long und er tr affic(low -polish resis tance). Sand stones of ten h ave th is tex tur e,and will m aint a in it quit e we ll und er tr affic beca use qu artz(a hard m ineral) is usually a major min eral comp onent.

As noted above, the s trength of th e cement h oldin g themin eral grains toge ther is a lso an imp ortant fac tor in th eperform ance of a sa nd stone. f the g rains a ren' t adequ atelybound toge ther, the agg rega te w ill b e wo rn away too

rapidl y to be acce pt able (low -wea r res istance), eve n th oughits surface tex tur e is maint ain ed .

Igneous a nd metam orphi c roc ks ge nera lly have the poten-tial to prov id e adequ ate pave ment f riction; howeve r, each

ock and Mineral dentification


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agg rega te so ur ce mu st be jud ge d on it s ow n m erit s, s inc esof t m ineral s can b e abund ant in so m e roc ks in th eseclasses as we ll as th e se dim ent ary class . Th e id ea l agg rega tewo uld b e comp ose d of one ve ry hard min eral and onem edium-h ard min era l. Ha ving tw o rela tive ly hard co mp o-nent s wo uld k eep th e ra te o f wea r at low levels. Ha vin g o neof th ese co mp onent s th at is hard er th an th e o th er wo uld 'ma int ai n th e s ur face textur e s in ce th e hard er min eral wo uldpolish slowe r and therefore rem ain above th e m edium hardmin eral at th e s urf ace o f eac h coa rse agg rega te piece .

Agg rega te s ur face tex tu r e a nd its res istan ce to p olishin g ca nbe jud ge d b y using ASTM D-3319, "Stand a rd Tes t Me th odfo r Acce lerated Po lishin g o f Agg rega tes Us in g th e Briti sh

Whee l" (ASTM , 1989a). "Th e In so lubl e Res idu e Tes t",ASTM D-3042 , (ASTM, 1986b) is used fo r ev alu ating th esuitabilit y o f ca rb onate agg rega tes for surf ace co ur ses.ASTM E-965, (ASTM, 1987 ) "S tand ard T es t Me th od fo rMeasurin g Surfa ce Macrotex tur e Depth Us in g a Vo lum etri cTechniqu e", can b e used to determin e th e pavem ent' ssurf ace tex tur e, and th erefo re so m e indic ation of it sdr ain age capa bilit y. The mi x d esig n and constru ct ion can

grea tly a ffec t th e pave m ent surface tex tur e o bt ain ediniti ally o n an as ph al t p ave m ent.

Impact Abrasion Resistance . The imp act and abr asionresistance of an aggrega te is determ ined b y testing using theLos A ngeles machin e (ASTM C-131 (ASTM, 1989b) for small-size coarse g g r e g ~ eand C-535 (ASTM,1989c) for large-sizecoarse aggrega te). The result s o f th ese tes ts a re ge neralindi cators o f aggrega te qu ality a nd may or m ay not rela te to

an aggrega te's s uit abili ty for u se in a pa vem ent sur face asdiscussed in th e sec tion above. Aggrega tes wi th hi gh losses inth ese tes ts degra de eas ily, and it m ay be diffi cult t o maint aintheir gradation durin g process ing. They may c rea te p roblem sby degra din g durin g mixin g in a sph alt or P ortland cem entmix es, o r durin g pla cem ent and comp action. These aggre -ga tes a lso may disintegrate o r d egr ad e rapidl y w hen expose dto traffic and the environm ent. Th ese tes ts, th en, ar e goo d

initial screenin g tes ts for di stinguis hin g the pot enti al p erfor-mance of an aggrega te. Foliated m etamorphic rocks have thepotenti al for hi gh loss, as do poorly cement ed sand stones a ndother sedim entary roc ks.

ock and Mineral dentification 5


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Particle Shape and Roundness Particl e shape m ay bed efined b y the ra tio o f th e thr ee prin cip al axes: length ,width , and thi ckness. Wh ere th e thr ee axes a re nea rly equ al,th e particl e m ay range in app earan ce betwee n a cub e a nd asph ere. Wh ere length and width are of nea rly th e sa medim ension, and also seve ral tim es th e dim ension of th ethi ckn ess, a flat particl e is d escrib ed. Where th e length i sseve ral tim es th e size o f both th e w idth and thi ckn ess, a nelonga te o r r od -shap ed particl e is pr ese nt.

A cub e may be diff erentiat ed from a s ph ere by th e charac-teristic kn ow n as roundn ess (or it s a ntith es is, angularit y) .Roundn ess may be d efined m ath em a tica lly by the a verageradiu s o f cur va tur e o f th e co rn ers o n a particl e di vid ed b y

th e radiu s o f th e ma ximum in scrib ed circl e. By thi s d efini-tion a s ph ere wo uld hav e a roundn ess o f 1 .0, w hereas acub e w ould h ave a roundn ess o f


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Their min eralogica l tex tur e consists o f sma ll d olomiti ccrys tals w ith in a matrix of clay o r silt and f in ely di videdca lcite o r b oth; a nd

The matrix is ex tremely fine-gra ined .

Wh en d ea ling w ith th e reac tivity pr oblem, the simpl es tso luti on i s to avo id th e use o f reactive agg rega te. With th eshortage o f ava ilable agg rega tes in some a reas, thi s is notalways poss ible. Us ing a low a lka li cement (less than 0.6percent ) o r cert a in admi xtur es has been a comm on pr ac ticew hen know n r eac tive agg rega tes a re used in concrete. Theuse o f low a lkali cement pr eve nts deleter ious expansion inmos t in stances. Mo re rece ntl y, some aggregates have beenfoun d to be dele teriously rea cti ve , eve n wit h the low a lkalicement s. This s itu a tion r einforces the need to tes t agg rega te-cement combin a tions before using th em on the job w her-eve r a reac tivity pro blem i s suspec ted . Definiti ve sc reenin gtes ts may take six month s to a yea r to run , but m ore rapidtes t m ethod s a re being deve loped .

Weathering . All of the above di scussio ns about aggrega teass um e that th e material is in a "f resh" un wea there d

conditi on. The mos t dur ab le rock, if expose d for a s uffi-cie ntl y long period to the natur al env ironm en t, w ill d egradeint o a so il. For mos t agg regat es, thi s time frame is geo log icrath er th an hi stor ic, and therefore, for e ngin eer ing pur-poses, need n ot be of concern . Th at is, it n eed n ot be ofconcern i f initi a lly un wea there d agg rega te is used .

In th e case of c ru shed stone, the produ ction of un wea theredagg rega te material can u suall y be ass ur ed by s tri p pingsufficient ove rburd en fro m th e site before ope ning thequarry , and durin g horizontal expansio n of the qu ar ry a tthe sur face . Sand and g rave l d eposits tend t o be moreva riable than cru shed stone qu arri es in both the horizont aland ver tica l di rectio n, so va riation in th e wea ther ing s tat e ofthe material m ay need to be more close ly monit ored durin gopera tions than with a cru shed stone qu arry. In eith er case,the deve lopm en t and opera tion of an agg rega te so ur ce

should b e ca refull y monit ored b y a geo logist , mate ria lsengineer, or o ther qu alified p erso n.

8 R ock n d M iner l de n t i f ic t ion


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Summary

Thi s manu al pro vid es a bri ef di scuss ion of th e form ation,comp os ition and class ifica tion of roc ks and min erals.Ident ifica tion pro cedur es a re pr ese nt ed fo r diff erenti atin gthe mos t comm on rock and min eral types the practicin gengineer is likely to enco unt er. The proce dur es may becarri ed out in th e field or th e labor atory using s impl e too lsand the flowc hart s prov ided . The a bility to id enti fy th eroc ks and min erals of w hich an agg rega te is comp ose d w illgive the engineer add itional in sight int o the potenti alperform ance of that agg rega te in a parti cular constru ctionappli ca tion. This abilit y w ill also help th e e nginee r tound erstand th e aggrega te's im pac t on th e perform ance(goo d or bad ) of pas t constru ction p rojects th at are beingrev iewe d .

For compr ehensive agg rega te id enti fica tion, tes tin g, andanalys is, a qu alified geo log ist, petrog raph er, or materia lsengineer should b e consult ed as ap pr opriate.

ock and Mineral dentification 9


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eferen e s

1. Woo lf, D.O . 1950. "Th e Id entifi ca tion of Rock Types." Pub lic Roads: vo l 26, no.2, pp . 4448. Bur ea u of Publi c Roa ds, US. Dept. of Co mm erce, Washin g ton, D.C.

2. Woo lf, D.O. 1951. The Identification ofRock Types Reprint b y US . Gove rnm ent

Printin g Off ice, Was hing ton, D .C. 11p .

3. Woo lf, D.O . 1960 . The Identificat ion of Rock Types, Revised Edi tion . U.s . Gove rn-m ent Printin g Offi ce, Was hin gton, D .C., Nove mb er, 1960 . 17p .

4. Hurlbut , Co rn eliu s S ., Jr. 1963. Dana s Manua l of Mine logtj 17th edition . JohnWiley a nd Sons: New Yo rk. 609p .

5. Woo lf, D .O . 1953. Results of Physica l Tests of Road-Building Aggrega te . US .Gove rnm ent Printin g Off ice, Was hin gton, D.C. 227p .

6. ASTM, 1986a C -294, "Stand ard Desc ript ive No m encla tur e for Co nstitu ent s o fNa tural Min eral Agg rega tes" , ASTM Annual Book of Standards Vo l. 04.02,Co ncrete a nd Co ncrete Agg reg ates .

7. ASTM, 1978 , "Signi fica nce of Tes ts a nd Pro per ties of Co ncrete-Ma kingMa terials " , Special Tec hn ica l Publi ca tion 169B, ASTM, Philad elphi a, PA, 8 _p .

8. ASTM, 1989a, D3319, "Stand a rd Tes t Meth od for Accelera ted P olishin g ofAgg rega tes Us in g Briti sh Wh ee " , AS

TMAn

nual Book

of Standards

Vo l. 04 .03,

Roa d and Pav in g Ma terials; Trave led Surface Ch arac teris tics.

9. ASTM, 1986b, D3042, " Stand ard Tes t Me th od fo r In so lubl e Res id u e i n Car bon-a te Agg rega tes", ASTM Annual Book of Standard s, Vol. 04 .03, Roa d an d Pav ingMaterials; Tr ave led Surf ace Ch aracteristics .

10. ASTM , 1987 , E965, "S tand ard Tes t Me th od for Meas ur ing Surf aceMac rot ex tur e Depth using a Vo lum etr ic Tec hn iqu e ", ASTM Annua l Book ofStandard s, Vo l. 04 .03, Roa d and Pavi ng Ma terials; Tr ave led Surfa ce C harac teris -tics .

11 . ASTM , 1989b, "Stand ard T es t Me th od for Res ista nce to Deg rad a tion of Sm a ll-size Co ur se Agg rega te by A bras ion and Imp ac t in th e Los A nge les Mac hin e ",ASTM Annual Book of Standard s, Vo l. 04 .02, Co ncrete a nd Co ncrete Agg rega tes .

12 . ASTM , 1989c, "Stand a rd Tes t Me th od f or Res istance to Degrad a tion of La rge-size Co ur se Agg rega te by A br as ion and Imp act in th e Los Ange les Mac hin e " ,ASTM Annual Book of Standard s, Vo l. 04.02, Co ncrete a nd Co ncrete Agg rega tes.



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