EIS 560

LADMIX111M

Comments on proposed Wheatly Quarry rock

IF Bc Coffv I\'IP'W Pty Ltd Wiluna SIreeL FyshwCk. ACT Australia. COFFEY MPW

Canberra. 2609 A( N (KI(.fl NSW DEPT PRIMARY INDUSTRIES Telephone: (61-6) 280 4732

- I Facsimile: (61 -6) 280 7940

AS 02 009 7 Telex: AA 151206

Dr. .J.L. Falvey. 1K. ulncn. ..aslam. Dr. B.C. Burman. Dr, J. Murray. J.E. Leake, J.W.A. Gildea. Experience Counts

II International Development Consultants

I . 4 February 1993

1 Grave Johnston and Associates 35 Scott Street Wolumla NSW 2550

Attention: Mr R J Johnston Engineer Manager -

Reference: Your letter TEST WUEAT of 4.1.93

Dear Mr Johnston

PROPOSED WIIEATLEY QUARRY

Mr Chris Turner of our Canberra Testing Laboratory has asked me to comment upon the petrographic and engineering properties reports on the samples of rock submitted for a'ialysis and testing in conjunction with above proposed quarry.

Please find attached my comments on these reports as requested in point 9 of your letter. Should you have further questions in regard to my comments I should be pleased to provide answers. You might raise any such questions, in the first instance, with Chris Turner.

Denis Byrne

I BSC, B.E., B. APP. SC. (Geology) Engineering Geologist

GENERAL\QUARYRK.MFW

Melbourne • Sydney • Adelaide • Brisbane • Canberra Bangkok . Kuala Lumpur Manila

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I References

COMMENTS ON (PROPOSED?) W1[EATLEY QUARRY ROCK

I - Letter Grave Johnson & Assoc. to Canberra Testing Services dated 4.1.93

- C.T.S. Report 93/ 22124 dated 22.1.93

- Letter Coffey to Bombala Shire Council dated 13.9.88

I- Petrographic Report (Hensel) dated 7.9.88

I note that there is a gap of nearly 4'/z years between date of the petrographic

I examination and report of (more weathered) surface spalls and the engineering laboratory testing of shot-hole" rock from 1-5m below ground level.

I assume, although this is not explicitly stated, that the two sets of data refer to essentially the same body of rock. The following comments are made on the assumption and to the extent that the data duly represents the body of rock intended for the quarry.

The rock type is described, petrographically as a microgranite. As such, and from the very 'detailed petrographic hand-specimen and thin section descriptions, this rock has a fabric texture and mineral assemblage which should incline it in unweathered condition towards a very strong, tough, durable and unreactive rock for engineering purposes in general.

This potential is borne out by the C.T.S. engineering tests of January 1993. Wet-Dry Strength variation of 16% with Dry Strength 290 KN and Wet Strength of 245 KN are typical for Granitoid rocks and, indeed, somewhat better than average. Los Angeles Abrasion loss of 15% is also a good result as indeed is sodium sulphate loss of less than 0.1% . All these "Texture toughness" type test results for this rock are consistent in Fresh Rock with its small grain size and closely interlocked matrix of essentially quartz and (both types of) fieldspar mineralogy. BuLk Density (fabric density or S-G) and Water Absorption were not, it appears, tested. These tests would, almost certainly, give results in the range 262 to 2.65 and 1.017a to 2.0% respectively, both of which would be normal and acceptable value ranges for this rock type.

The "Processin Properties'of radi , particle shape, and Averae Leastg gng g Dimension are significantly dependent on the crushing, screening and possibly washing processes employed in the manufacture of a crushed rock product from the quarried rock.

GENERAL\QUARYRK.MPW

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As such, I am disinclined and it may be misleading to comment on the values obtained from a trial crushing of a small quantity of the rock. -The rock fabric texture, as petrographically described, makes no mention of any microfabrics or micro frac turing which might incline the rock to a poor particle shape. This rock should, therefore, be able to produce crushed aggregate of good particle shape, assuming use of appropriate crushing techniques. Product grading is then a function of screening process and, possibly, washing.

Concrete Aggregate

This rock, in its fresh state and appropriately processed, should make good concrete aggregate. The strength and validity of any Feasibility Study (and certainly any later stage study) would be enhanced by a second series of testing. These tests should comprise, at least, Bulk Density, Water Absorption, Wet Strength/Dry Strengthl Variation tests and a Mielenz Test for potential reactivity (although the present petrographic descriptions do not alert to the presence of any potentially reactive mineralogy.

Sealing Aggregates

The petrographic report alerts (on page 1)_ to the possibility that bonding problems may ari.e because of the presence of secondary white mica (sericite in the modal analysis) and clays. I would not consider that the accessory to trace proportions of these minerals present in this modal analysis would have been of great concern. Nonetheless, this aspect can be and should be checked on typical crushed aggregate intended as sealing aggregate by the Bitumen adhesion (Resistance to stripping of cover aggregates and Binder) test. This test should be conducted with and without precoat adhesion agent to check on the hydrophilic properties of this rock type and the polarity differences between the rock and bitumen.

Microgranite as a fine-grained and hard rock with plentiful quartz content may

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be susceptible to polishing under traffic, but this susceptibility is influenced by many factors including road geometry and traffic density. It is most reliably

Ijudged in service.

Crushed Road Base

Crushedfresh rock with or without the addition of fines (perhaps from the z . more weathered zones) is, of course used as road base or subbase in road

pavement construction. This rock would seem to have the potential to produce or form the basis of good quality crushed road base.

GENERAL\QUARYRK.MPW

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If this is an intended market I would strongly recommend carrying Out the necessary Grading, Atterberg, Particle Shape and WetlDry Strength tests required by, for example, RTA (NSW) Specification 3051 Table 1 to establish compliance with this Specification for a typical crushed product.

Additionally, consideration might be given to carrying out Texas Triaxial Tests on representative material to enable compliance with RTA (NSW) Specification 3051 Table 2 to be also established. I understand that Current RTA pavement design is tending to use Table 2 Criteria rather than Table 1.

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D AByrne Engineering Geologist 4 February 1993

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GENE RAL\ Q U AR Y RX.MPW

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Canberra Tesling Services A Ct,I.0fl 04 JaQ'q ly LtO coo,at.ri in NSW ACN 002 731 76

Reoort no: 93/22124

CT bO Wituna Street,

Fyst'r.ck Carrb.erra ACT 2609

Phone 10621 80 4261

concrete aggregate test results Client: Crave Johnston c Associates

proect: Proposed Wheatly Quarry Site

location: Bega, NSW date; 22/1/93 job no: CTS1088

sample no: 22124 ,aggregate source:pr000sed Wheativ Quarry Site, Bega, NSW, sample received on 4/1/93

date tested: January 1993 descruptOn of material: ')rinrj

AS tIll

SectiOn test descrtiort range tested test result A.S. limits

4 unit mass . gfm 3

5 bulk density and aser bulk densüy kg/mi

absorption of tine aggregate bulk density (S.S.0.1 kgfm

absorption

6 bulk density and water bulk density

absorbtion of coarse aggregate bulk density (S.S.DJ k9/m 3

absorption

sieve analysis 75.0 mm

it 0 0 0 530mm Q 0 0 50 ucorvotasoC ____-_---------------1 rt :mcsor'-.c-,srs 375mm

26.5 mm

-. 19.0 mm 1 -

13.2

9.50mm I I 6.70mm -

11 - ±—----— [ 4,75mm

50 2.36mm 17 • _____ ________ ''i'

- { 1.18mm

600pm '9 IF

300pm 5 • i II = : : 150 Um 3 _______

75pm 2

12 material finer than 75 p rn

13 material finer than 2 pm

14 Oar tide sJ-tace - mis-shaven particles 2 : 1 —19 . Q-r-9 .5mm 31

*20 averace least dimension * mm 4.9

21 aggregate crushing value

22 tO oercent fines value wet/dr;/variatjpn kN 19+9 - 5mm 245/290/16 23 resistarice to abrasion by lot angeles machine % F19+9 . StilIfl 1 15 1 24 1 soundne by use of sodium sulphate solution) % H13 - 2+2 . 36 008, 31 light bartiCles

32 friable Oarticles

34 organic impuritieS Other than sugar

35 sugar

39 Potential reaOtrvity of aggregates Sc = mmolIl

(chernical method) Sc mmol/l

remarks Polished Aggregate Friction value = 50 (tested by others)

*Separate certificate

Aurhorised Slure

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This laboratory is registered by the National Association

of Testirç Authorities Aurtralia. The test(s) rorted herein have been performed in accordance with the terms of regstration. This document shall not be reproduced e,iceOt in full without the priO( tçroval of the laboratory.

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BORALRESEARCH J.

Materials Laboratory A.C.N. 000 756 507

Boral Resources (NSW) Pty. Ud. Greystanes Rd (P0 Box 42)

Wentworthville NSW 2145 Australia Telephone (02) 688 9901 Facsimile (02) 688 9813

POLISHED AGGREGATE FRICTION VALUE

CLIENT: Coffey Partners International

FILE NO: 56/93

PROJECT: Testing of spalis for P.A.F.V.

PRODUCT: Spalls

LOCATION: Unknown

SIZE OF AGGREGATE: -13.2+9.5mm

LAB. SAMPLE NO: 87

DATE RECD: 12.1.93

Samples were prepared as per AS1141.41 and tested in a wet condition as per AS 1141.42 prior to and after polishing. The samples were polished using the procedure of AS 1141.41.

A reference aggregate sample, Panmure Basalt" is included with each testing run. This sample acts as a control on test performance and is used to standardise the sample results. After polishing the samples were again tested in the wet condition according to AS! 141.42.

Test Method Results Panmure Ref. Sample PAN 'B'

AS 1141.41 Sample mean friction value /42 -1984 corrected for temperature 73 75

before polishing

Sample mean friction value 47 48 corrected for temperature after polishing

Polished aggregate friction 50 - value (PAFV) after polishing

The air temperature during the friction test was 24°C. The sample mean friction value corrected for temperature 23°C.

Sample submitted by client. C. Turner, File, Ref: Rep.013

—

—. Authorised Signatory Richard Bawer

Date 22- Serial No.

VAI'l fr., abO'aWey 1 ç:1l,*d Dy (fl. Nfl,Onai A,TOC.abOfl 0$ T.iItg AvfhO,t., Aq31tM4 rae cc:s ,.00e,.a a.,.., a,..0 ø..a p.rlOm,0 n ICCO.dSflCt

TA an 41 fern,, 01 ,eq,lf,.iCfl Ta., ØOC,nfl, 1/fCC n*i O# fID'OdfiCeC •CIQf if' (.4

Coffey Partners International Pty Ltd

soundness of aggregate COFFEY rwnple no:

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Lab No.22124 Ph eet 1 of 1

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office: Sydney

client: CRAVE JOHNSTON & ASSOCIATES 1ob no: CTS 1088 principal: ci 20/1/93 project: PROPOSED QUARRY SITE tested by: MC location: BOMBALA,NSW checked by: JR

testprocedure: AS1141 Sect.24-1974

aggregate source: CTS—Canberra rrmterial description: Aggregate

ajiution used: Anhydrous Sodium Sulphate

sieve size S oessing (at received) S loss after test weighted loss %

13.2mm 78 0.0 0.0

9.5= 62 0.06 0.01

4.75= 26 0.09 0.04

2.36mm 17 0.26 0.03

Total Weighted % Loss = 0.08

examination of particles greater than 19mm

no. of pieces before test:

no. of pieces after test:

type of failure observed:

remarks:

This leborator'' is registered by the National Asrociation J. RUSSELL / 1 3 of Testing Aurflorities, Australia. The test(S) reported hereinhave been perform-ed in .ccordsnca with the terms

excrs in full wiout the prior a000vel of the boratory. Authorised S#gnaturr of registration. This document xhjll not be reproduced

th

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COFFEY

I Cotfey Partners Internatlo nal Pty Ltd Consulting Engineers

ACN 003 692 019 in the geotechnical sciences

12 Waterloo Road

test results North Ryde Sydney 2113

SYDNEY LABORATORY

I princpal:/Cljent: GRAVE JOHNSTON & ASSOCIATES project:

location:

PROPOSED QUARRY BONBALA, NSW

SITE date: 27/1/93 job no: CTS1088

teasprocedure: AS1141 Section.20-1982

Average Least Dimension

Sample Identification mm

Lab No 22124 4.9

Note: Sample supplied by CTS - Canberra

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Th ts LaborltOry rs r stared by the Nionl Aociation

of T.,iing Autrodt... Auetrha. Tho tt(s) rvooried h ire ahiv beet, oerlocrnod in Ord.ertCa with the t.rtT

of regirtration. This docustant I,.all not ba r,oroO.c.d

excQt in full without the prior approval

,f

the laboratory.

J. RUSSELL2/ / /3 Auth or i S- qna

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GuffEy

Coffey & Partners Pty Ltd Sod C* flQ

9VV* GOçy Szcn -

QUS -5

ow. .. ... q N.

£ GKS:VS — C.1097/1 13th September, 1988

Shire Engineer Bombala Shire Council Council Chambers 17 Caveat Street BOMBALA N.S.W. 2632

Attention: Mr W. van Leenwen

Dear Sir,

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Consultinq Ençineers in the geotechnic.aI sciences

IncorpOrated in Queensland c. 8c W'iluna Street Fyshwick Canberra

P0 Bcx 152 Fyxhck ACT Australia 2609

Fax (062) 80 7940 Telephone (062) 80 472

RE: PETROCRAPHIC ANALYSES OF SUPPLIED ROCK SAMPLES - PROPOSED QUARRY SITE, BOMBALA, N.S.W.

Please find enclosed the results of petrographic analyses

performed on two supplied rock samples, including comments

on potential uses of the quarried rock.

The rock samples are understood to have been obtained from

the ground surface, occurring as spalls or outcrop. As such,

the rock samples are weathered and altered. On the basis of

these two rock samples alone, potential uses are very lmted.

In addition to the above rock samples, drill chippings were

supplied from four boreholes, designated 2L, 2R, 3L and 3R. The

drill chippings have been visually examined, and based solely on

this visual examination, the rock appears to become slightly

weathered or fresh at the following depths:-

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Cotfey & Partne(s Pty. Ltd.

GKS:VS - C.4097/1

Page 2

* borehole 2L:

borehole 2R:

* borehole 3L: * borehole 3R:

below 6m;

in excess of 12m;

in excess of 9m;

below 3m.

Quarrying of the slightly weathered and fresh rock is likely to

extend the potential uses, into possibly concrete aggregates,

base and sub-base materials in road constructions, and road

sealing aggregates.

Please contact this office for any further information concerning

this report.

Yours faithfully, COFFEY & PARTNERS PlY LTD

DR C. K/SPENCER

UillEiry ffE

Coffey & Partners Pty Ltd CoUng &Qireei in the geoteca cience.

Icopotaed in OeeriIarx lr

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PCThom.on - MO P?M

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I... CKS:VS - C.4097/1 24th. October, 1988

our tlecer.cr

date

Shire Engineer Bombala Shire Council

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• Council Chambers

- 17 Caveat Street RflMRAI A NW 767

OBt2 FACT

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Fax P62) Te4epne 472

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Attention: Mr W. van Leenwen

Dear Sir,

RE: PETROCRAPHIC ANALYSES OF SUPPLIED ROCK SAMPLES PROPOSED QUARRY SITE, BOMBALA, N.S.W.

Please find attached the results of petrographic analyses

performed on three rock samples, selected from a number of

samples supplied, including comments an potential uses of

the quarried rock.

Please contact this office for any further information

concerning these results.

Yours faithfully,

COFFEY & PARTNERS PTY LTD

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CDHMES 1 These t samples of feic igneous rock are songly YTvathered and aered. They appear to be surficial spalls and therefore are not truly indicative of the physical

I- characteristics and properties of the underlying rock. It is strongly recommended that a

sample of fresh rock - such as that to be quarried or excayated for t intered application - be examined to establish mole-applicable and representative

I characteristics A bore-core1 which presumably has been sunk to establish reserv'es, 'uId be quite appropriate for testing.

I Based only on the samples supplied the following comments can be made on Its durability and potential use.

- The fine grainse and interloddng texture giYe the rock considerable strength and toughness. This translates into good durability and suitability for a range or

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applications. The amount o(car-bonate is of some concern because of its mobility in - solution. However, the concern does not extend to reaction with suiphide because of

the apparent paucity or the latter. The high percentage of brownish hydrated iron

I oxide as films, infihlings and yeinlets detracts from its appearance because of the mobility of the iron in solution (results in staining). FurtherTriore, the iron oxide films reduce the adhesion between rock and bonding substances, such as bitumen and

I -ce-ment Additional bonding problems could arise with the hh proportion of seoridary white mica and clays because of their flaky morphology and water

I exchange capacity.

rc could be eeoted that the rock vould be sLIbnUally less-aitered at shallow depth and that some of the shortcomings fof its use in concrete and as sealing aggregate

I may disapoear.

Depending on the field occurrence the fresh equivalent of this rock might be

I particularly desirable as a building stone for use in external and internal wall cladding, excehent for paving, reconstructed granite panels, aggregate and road base.

I Assuming the rock remained as attered as the samples provided the best applications - ufd be road base and sea-ll or retaining wall constidns.

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I Dr. ft ft Hensel (7th Sept., 1 988)

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I• Ncroscopjc description of rock

I A. hard, athered, bleached and apparenuy leached, flngmined, dominantly pink-

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coured gnic rock with numerous Yugs and pi. The SaMPIe is songly sined and obious1y represen a uaace spa!!. Most of the pit and Yugs are so(uUon

cayes but some appear to be miarolitjc caYies produced dng high-yotjJe hh-flUjd insiye actiylty. A dense spdnkling of a green minel and patches of a

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so whsh minef indicate consjdele hydrothermal actiYty during andr after emplacement

I Petrographjc description of thin-section

I This is an unusual Ielsic igneous rock consisting basically of numerous, rough ly circulaf microghic Suctures, refatieIy large euhedI crystals of pIagise

fc-ldspar and abundant intetitial patches of late-foned mine. The rock is hhly

I altered through both deuterjc and surticial processes

The mrogphic suctures songfy resemble radiaUng rosees common in felsic I exusiye rocks. There appear to be two cmon sizes - one around 1

mm the offier close to 0.4mm. The cenes of both are exeme

nei in diamete

ra ned - from unresolyle to around 5. Grainsize increas mply oud fing the claic

I microcphic intgroh of qu and aali felds. Many of these Sures are composite corining 8 septe pooy foed and genl

eç ne-gird unt. In some part, reIatiely rge (uo to 2mm ng) plaioclase are I ndomjv

disbuted 8ecause thcslIized earlier than the aiali feldso these long crystals appearto constite nuclei (or the late co ste uctures.

I The pgiocJase feldspar is thorouhly aered sLh that only in a few insnces is any of the ongina; mneRj preseed A.lthougn mostly unresolyab it appe

that The replacement P(-OdUcts are sericite, conate hydated iron ox;e and cy. 4. ond I gentjon of plagioclace feldspar is presert in the te-sge ieha[ infiili cornposn is alb with nudimnerty tns. ngs.

lts

I Most of The quartz, and siIy the alkali fefdsp, is tied up in the intgro .

HOyç1 a small pr000thon has csllized late as free qUaftz and aali feldsp ar

I csIs In most of these inteial patches it is clear that ysl1ization occued unr ter-satuted conditions withw1_11-rorm d cnysl faces and bipidal terminans on the quart not uncommon.

I Aociated with these satuted conditions is conae biotite and chlorite. None of the original iron-rich biohte remains inct haying been comptely chloritized. The

I onate istely to haye originated by the decalci(ition of the pgioclase Feldspar although an external deriyatioc nnot be ruled out.

A small amount of Cah)orjate is disuted.ndomJ).' throughout the rock as riiomhs indicating subst.anti.l fluid mobili through the rock aer ccysllization There is also a small sca.erirg of a feTomagnesian

I minef throughout the rock that crysllded . early. Althoug likely

to haye been biotit there is also a Possibili.' that Some hastingsitic amphiL.ole crysllized under these conditions.

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The redness in the rock is due mainly to the presence Of abundant small concentrations, Yeinlets and fflms of hydrated iron oxide - probably goethite. In places entire plagioclase feldspar crystals have been replaced by goethite-stained secondary minerals.

Slender, subhedra[ crystals of zircon and small specks of magnetite and'or ilmenite are the main primary accessories.

Mode of rock

quart 28% alkalifeldspar- 38% plagioclase feldspar 20% secondary thite 2% sericite 1% carbonate 3% chlorite 5% original biotite tr hydrated on oxide 2% accessories 1 %

Name of rock Aitered micrographic mcrograne

onibaLa area 2

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. Macroscopic description of rock

Yery similar comments to sample 1 Mth the exception that there is a decrease in the

I -.. proportions of greenish mineral and soft whitish mineral and a slight tendency towaçrds a pale yellowish-green.

I Petrographic description of thin-section

In most respects this rock is very similar and closely allied genetically with sample 1.

I For this reason only the most obvious dierences are highligted. Texturally there is little difrerence beten the tyo because of the dominant radiating micrographic

-. sbuctures, interstitial patches and indistinguishable grainsize. Similarly, the extent

I and type of alteration of the Ieldspathic material is virtually identical.

I .However, there are some mineralogical differences. Most conspicuous is the presence of fluorite accompanying the late-sge minerals crysllizing from a fluid-enriched system. Another is the development of clay balls in some of the interstices,

I not infrequently accompanied by goethite. These clay balls (<0.5mm) appear to be composites of illite plus kaolinite variably sirted by hydrated iron oxide. Another is the dramatic decrease in the amount of deep green chlorite. Furthermore, the

I .alteration of original biotite is clay (?smectite) dominated rather than through chioritization. Collectively, these features indicate a lower temperature during the deuteric and surficial alteration sges. The presence of the clay and flucote as

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.late-sge intHlings may be cont-ibuting to a slight decrease in the proportIon of carbonate in this rock.

I A primary mineralogical derence, which could perhaps be sampling-related, is the presence of slightiy more, euhedial plagloclase ciysls around which the radiating s -uctures have nucleated. Whereas in sample 1 it was diticuit to find remnants of original piagioclase feldspar in this rock there are several crystsds with only moderate alteration. The alteration also in this sample is, in places, quite coarse white rmca (accompanied by some goethite). Another primary feature is the decrease in the amount of long, thin ferromagnesian cysis that may have been hastingsitic

- amphibole.

As in sample 1 the principal accessories are zircon (both elongate and srr.11 subrounded varieties) and magnetite. The paucity of sulphide in this and probably sample 1 may well be real; however, the extent of alteration is likely to have removed most, it riot all, existing suiphide and replaced it with hydrated iron oxide.

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Mocroscopic description of rock

- A. hard, tough, very fine-grained, greenish-pink rock with very thin Yeinlets and a scattering of small, Clear patches.

Petrograptiic description of thin-section

This rock consist mainly of sirrall micrographic suctures, ee quart and aflc

I feldspar around miarolitic cavities, carbonate filling these cavities, a small amount of white mica and chlorite and minor fron oxides.

Alterationis princiDally hydrothermal and may have occti-red at any sge alter the cryslJizaUon of the rock. The main effect of the aiteration have been to corrert the biotite to chlorite, in -oduce carbonate and pepper the fe!dspathic componenis of the rock with secondary white rriica (sericite).

The micrographic sfructures dominate the rock. The majority range in size from 0.1mm to 0.6mm with a few larger ones extending this range to 1.0mm. Few are rounded because of the raDid nucleation and impingement during 07siz1!ization. lntercrohs are quite fine with a pical se at the pehmeter of 0.01mm wide and 0.07mm long. Ahough there is some coening outrd many of these sctes show lie gradation in the size Of the intergrovths.

I Small, single euhedral plagioc feldspar crysb occur rar the cores of quite a few of these mrocraDhjc sctes. Scatter large crysls may exce 3mm. Small albitic feldso arcrysls may also accompany some of the qu in the mo(itic cavities confirmina late-magrnatk hrothermal acUv. Mo of the fe

,~dspar is rniy to moderately altered and replaced ' sericite. In zones of relatively intense

I se-ncitization crainsize may asprcach 0.0rnrn, eeciaf1y in the thin, con'olLed, discontinuous Yeinleiz. For the remainder of the rock much of the ite iz around 1-S, and not une the bype of alteration asiated with kaolinization.

I Chlorite is vually resed to late-sge fluid-rich patches and molitic cave. it forms small greenish clu o 0.4mm) and is quite on-rh. In several insnces it

I clearly replaces biotite pseudomorphing the original shape.

There are ao spe opaques o 0.2mm) that appear to be py altered ,-Y-Tli

magn-etite and a scattering of very elongate prismatic crystals that now appear to be repced by hydrated ironoxides.

I Carbonate (calcite) occupies the miarolitic cavities and also forms small isolated rhornbs within the micrograph sures. Interestingly, quite large zcons o 0.2mm) may accompany the carbonate in some of these cavities. Other zircon is reasonably

I abundant and there is a sb-ong assoc ia.tn with majnetite. -

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j Mode of rock

-. freequartz 5% ttee feldspar 2% mkographicsruthres .75%

I. pgiocsefeldspar 5% chlorte 3%

• . rbonate 4% 1 serice 4%

ZrCOfl <1% opaques 1%

. hydrated hon oxide 1%

Ivugs

Nome of rock Microgranophyre

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Macroscopic description of rock

A hard, weathered, bleached and apparently leached, fine-grained, dominantly pink-coloured igneous rock with numerous vugs and pits. The sample is sbongly fained and obiousIy represents a surface spafl. Most of the pits and vugs are solution cavities but some appear to be miarolitic cavities preduced during high-volatile, high-fluid inb-usiye activity. A. netod of one or more dak-coloured minerals and sparse patches of a soft, whitish mineral indicate considerable hydrothermal acth'ity during and/or alter emplacementi

Petrogrophic description of thin-sectIon

This moderately aered, songly oined lelsic igneous rock consists basicaly of numerous, roughly circular micrographic sbuctures, a scattering of relaUely large plagioclase feldspar ci-ystsis, concen -ations of quart around cavities and a sprinkling of muscoye

Aithough the alteration to this rock is both deuteric (late-stse magmatic) and surf ida! U it appea to have had only a minor ect on the cyeraU chemical siI1 and sength

characteristics.

The micrographicsucturs which are an intergroh cfaaUfe!darand qu are Yen>' siilar to radiating rosettes common in lelsic exfrusive rod<s. The princal

I - derence is that elevated thermal conditions at the time of emplacementor eXfrusion we allod relately slow cr/stslllaatidn and therefore a coaening of the inLerçroh.

The micrhic suctures in this rock are typically been OAmm to I .0mm aoss. nes tend to be Yen>' finerainedcosrsening oLrd. 8ecaue of their abundance ncral deve !opment has been rescted and many ap,pearto be rFi

IEuhedral plagiocFase feidsoar crysts!s are ranndmt7' scaeredthroLhout the rock and cut across several of these microghic structures. Most cstsfs are around O.S to 1 .0mm but several othera exceed 2mm. Because of their early a7sts1lization these I well-formed feldspars acted as cenbes for the nuceation of the mrogmphc U suctures. The plagidclase feldspar varies in it3 freshness from mildly aitered and

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reining twinning features to totsily sericitized and kaolinized.

Most of the quarts, and sftnilarly the alkali feldspar, is tied up in the intergrovths. However, a small proportion has crystsflfzéd late as free quart around miarolitic

I caYes. In these interabial patches crystallizatidn occurred under ter-saturated conditions with some well-formed crysl faces.

I Although no longer present biotite vas probably the only lemornagneslan mineral to crysllLe It has been tlly replaced by hydrated iron oxide and secondary white

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mica. There has been a suhstsntjal infroduction of hydrated iron oxide probably goethite) into this rock Yia a nehwo ci fractures. Many of these fractures are between 0.0mm and 0.1 0mm wide. The e:tent and frequency of these fractures may be an importsnt consideration in the eventual applidatidn of this rock.

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A few rhombic shapes are scattered throughout the rock but mostiy occur within the cores of micrographic structiies. They a!most cerinly represent carbonate that has been removed by solution.

The extent of hydrated iron oxide introduction coup(ed with the hydrothermal acUvity etrectively mask any originaliron-bnium oxidesThat may have crysilized.

Hode of rock

Iteequasiz 4% micrographic strud:ures 78-80% plagioclase feldspar 5% hydrated iron oxide cavities 4% white mica 2%

Name of rock

Altered m icrograp h Ic s ubvo [canic mb-us lye (m icrogra flop hyre)

Hcroscopic description of rock

A. greenish-pink, altered igneous rock with numerous small cavies some of whih al-c filled with a soft whitish mineral. Bands of brownish-coIo -ed alteration trayerse the I. Petrographic description of thin-section

Texturally this rock is similar to the previous 2 in tt t prtnary mineralogy consis ts I mainly of numerous patches of micrographic intergroth, a small amount oliree quait and albitic feldspar associated with miaro(itjc cavities and fluid Concenb-aLions early cristallized but generally ll-aitered pIagiocse feldspar, opaque oxides and some I zircon. Its secondary assemblage consists of sericite, illite and smectite clays, probable kaolinite, and hydrated iron oxide (goe-thite).

Because most of the primary mineralogical features of this rock haye been deiled in previous descriotions only the difterences will be highlighted.

The most significant feature of the rock is its advanced alteration. The rock has carly undgone a couple of cycles of alteration such that earlier s,&condary minerals (e.g.

I carbonate) have been dissoiyed and replaced by illite. Thus ille occt., ies the miarolitic cavities, small patches near qua-1eldspar pods and in her inLetitial areas. Sehcite replaces mostly the sodic oligocse feldspar but Fcs paern and

I intensity appear hapharard Some clusters of plagicdase feldspar are tots.lIy repced by sehce whilst nearby aystals are virtually unaffected. Sericite also repces original fenomagnesian minerals rinciDally biote) where may be joined by smtite. Hydrated on oxide is inoduced v fluids at any time after emocement of the rock. In this case the goethite occupies numerous le ctur, coats caYits and qu -

feldspar catches, rfaces other oxides or feomagnesian minerals, or

i simply occupies the grain boundaries bet-en the micrograr h sbuctures.

Kaolination of the aLkali feldspar Uvoughout the rest of the rock widespread; I - howeyer

precise extent is masked by the abundance of tiny flakes c'sericite.

I 4ode of rock

free quart 4% freefeldspar 2% I - rnicrographic sb-uctures 65%

- plagiodase feldspar 12% sericite 4% I - zircon <1% opaque-s 1%

- illite 3% .. kaolinite 3%

5fleCite <1%

I . hydrated iron oxide 2% vugs 4%

I N me of rock Altered microgranophyre

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