N OT $ S O N PRO S P$ CT I N G

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I N T$ $

F$ D $ RAT $ D M A L A$ S TAT $ S .

V B. S CR $ R . NO J I ,

Geol o is t t h F d t d l a S s fl t g o t e e e ra e M a y ta te Gover m e n .

$ UALA LU M PUR : I D T T T . O T $ $ F. M . V M PR N E A S G ERN EN PR ESS .

— - 6 1 1 .

$ N S CONT T .

P R O SP $ C T I NG D ET R I TA L D EP O S ITS I N T$ $ GRAN I T $ $ I LLS

I - $ I . P R O SPECT I N G N O N D ET R I TAL D EP O S ITS IN T $

G I T $ $ I 0 0 RAN LLS 0

I I I . P R O SPEC T I N G A LO NG G RAN IT $ MAR G I NS

IV M . P R O SPECT I N G A LLU V I AL FLATS AN D A LLU V I U I N T $ $ L I M ESTO N E $ I LLS

P R O SPECT I N G D $ T R I TA L D EPO S I TS BELOW T$ $ R EC EN T A LLU V I U M

$ A D V I . P R O SPEC T I NG V I NS N P I PES

I T I O F P O T I S M S — P O V I . V A LUA N O R SP EC N G A PLE R SPECT I N G REC O R D S

L T R T I ONS I L$ S A . — Figu re I . Section show ing th e S t ru c t u re o f th e $ inta Va lley

b e fO Pe the Fo rm a tio n o f th e Limestone $ ill s .

— - h Figure I I . S ec tio n sho wing Al l u v ial Beds with Pay dirt at t e

- Base Lyin g o n Limeston e Bed rock .

- i h Figure I I I . S e c t o n show ing th e same Bed s after t e Limeston e

- b W Bed rock has bee n attacked y ater .

I N T R O D $ CT I O N .

The following n ot es on prospecting for tin - o re in the F S ro m te d a rtl w ederated M alay tates have been p p p p y by hat is n o w Obvious to all of us , the approaching exhaustion of easily won o re near the s urface in localities where tran s port is cheap; and partly by the fact that certain prospecting operation s u ndertake n in the last tw o o r three years have been s o . ” l w o f misapp ied , o ing to lack appreciation of the structu re of the w l i w grou nd being dealt ith , as to resu t in noth ng but a aste of Capital and an unfortu n ate impression on the part of tho s e who u ndertook the w ork that the country is n o good .

~ M a y own practical experien ce of . prospecting is not l rge , and I am aware that in addre ssin g these lines to the min ing com mu nity I am attempting to advise many whose practic a l experienc e h a s been spread over a greater n umber o f years than my o w n ; but I t rust that it w il l be recognised that my obj ect i s s not to criticise , but to turn to accou n t Opportun itie of o n e w o ne h c omparing m in ing district ith an other, an d m ine wit t w another, ogether with a certain amoun t of special kno ledge , in ' a n e nd e av o u r to s ave useless expend iture an d in show ing to Som e exten t ho w much value S hou ld be placed o n the re s ult s obtai ned w - u s he n prospecting grou nd for tin ore . M istakes have do btles o been made here in the valuatio n of mining pr p erties , as they have been made in every country possessed of considerable mineral w ealth . I n this country som e such mistakes have resulted from unlooked for peculiarities in the structure o f the groun d o r from the fact that some tin deposits upset calculation s by behaving in a

w - w man n er different from ti n deposits elsewhere . I n a ell kn o n $ work t h e follo wing passage occurs M iners w ith fixed ideas resulting from ob s ervatio ns made in a limited area are co u se quently/ liable to m ak e s e rio u s mistakes when they attempt ” to apply their experien ce i n distan t a nd totally n e w localities . ' t I w i The liabili y , as have reason to kn o , is not conf ned to

w m an n e w. m in ers ; but hether a be m iner or geologist , in a b u t ‘ re v io u s country he has n othing to guide him p experience , w and rightly or rongly , capital is not kept idle , nor are min e rs w required to ait , while scientists make a protracted an d careful examination Of the groun d to be m ined i n order to g u ard a gainst mistakes . We stil l learn by experience an d comfort ourselves w ith the refl ectio n that he wh o m akes n o mistake s m akes nothing . m , w d These notes hich do n ot preten to be a co plete. r w n t eatme nt of the subj ect , are ritte solely for the mining

I d . commu nity in this country , and therefore have refraine from

s w Of w . takin g, up pace ith a description the properties by hich

s ‘ ” a i ~ 9 . A Treati s e o n Ore D e o si ts Ph illi s an d L ou is . 93 A. p , p , p p , 2

- s tin ore may be recogni ed . I do no t mean that th e re is n othin g to be s aid on the subj ect w orthy of attention : on the contrary tin - o re sometimes occurs i n extraordinary forms that escape recognition even here , and may escape recognition when there ' is n for h s uc l i ss . s o ne n o apparen t reaso e us ven e The ubj ect is , ' however, that Should b e tre ate d at length in order to be of real u s e “ a n d e and e to meet every case that has com under n otice , thes s I p age do not seem to be the place for such an attempt . I f

' m a u w o f w w o n e ' thin k y tter a ord arn ing , ho ever , let n o he . ' k now s a p hrase that o ne hears occasionally among

'

- m b s . m o f e t iners , ecau e it is a atter gen ral experience hat ' w s ub ect m a S Of , S hOW S h ho ever simple the j y appear tudy it . t at

s a n . C s e m more remain to be le r ed as iterit , as a in eral species , ' d oes n o t attract the . min eral ogist by any characteristics of s especial crystallographic or chemical intere t , but a long

experien ce of the mineral as an ore has taught me , that if anyone

‘ s uppose s he has come to an end o f s erviceable k nowl edge

‘

l w . concern in g it , he is like y to find he is rong

I n s v the last ection of this paper , on the aluation of ' ' r e s w e a m p osp cting amples , it ill p rhaps appe r to so e that I e n s r advocat a method that errs on the S ide of u n eces a y accu racy . ' is o f in t i s a m l e s f ro m There , course , a limit reat ng p prospectin g r fo r s work beyond Which it is u n necessa y to go practical p urpo e s . Fo r o n instance , it would be u nreason able to in sist results being w o f ' o r tw o orked out to three places decimals , even , in the n s m aj ority of ca s es . But has a ything occurred in thi coun try to S h ow ’ that p rospecting i n t h e past has bee n un nece s sarily accurate $ I was frankly told o n o n e occasion that my method o f “ $ re a rin s am l es the p p g p is not practical , b ut I defe n d it o n gro u nd that the most practical prospecting is the most accurate w w prospecting, ithin the limits indicated above , and that here ' u s te rlin m a w thousands of po nds g y be involved , it is rong to refuse a ne o f w to av il o self simple means that ill elimi nate some , at any o f a w racti rate , the errors th t vitiate hat my critic meant by p ” '

l w N S m . w o rk . a n w ca ork o an e ill claim that prospecting J ' ‘ w w x th e v al u e ho ever elaborate , ill give an e act figure for of the u a w e to gro nd . It is an pproximation on ly , but should try get as n ear the exact figure as may be by searching for all possibl e .

sources o f error and correcting them if w e can . I have quoted passages in this paper from Phillips an d Louis ” ” s o n - O re D w wh o Treati e eposits , and ould recommen d all are i nterested in min ing a n d prospecting to read that or som e Othe r such w ork i n order that they may appreciate bette r: than they w h o w w could from anything I might rite here , important a kn o : ledge of th e 's tru c tu re of the grou n d o ne deals w ith is to those h h w o prospect o r w ork it . I t is n ot suggested t at every miner u w th e o f fo r sho ld, be on fam iliar terms ith legio n rock species

' Which recognition has b e e n ‘ c l a im e d ‘by various a u th o rs d u rin g . a h to to a past ye rs , that he s ould be able assign bed its correct ' ‘ ‘ eans o t e osi o r w l e age by m f f h f s l s it contain s , a k with ase amon g n the signs and s y in h o l s of a text boo k of: mi e ralogy . What I s claimed 13 that every miner should take advantage of such know l edge as has been obtain ed by train ed men in order to save money s by raising prospecting above the level of pure luck and n umber , which have been the basis of most prospecting successes i n the o rld w w e l , although accompanied by hat hear litt e about .

w a n s . disappointment to many , asted capital , and severe priv tio

w t o I II l I k no , o , that the recognition of certain minerals sma l o ne s is f grains , such as gets in pro pecting samples , a very di ferent ‘ o f the matter from identifying good laboratory specimen s , same mineral when taking a course of mineralogy . A concentrate from‘ tin bearing groun d frequently contains mixtures of heavy w minerals , and it ould be absu rd to expect every miner to be able i o f - to g ve an accu rate analysis such mixtures , or even to i nvest i n a petrological microscope as an aid to p rospecting , si nce such w ork requires ca reful train i ng an d long practice before confidence e can be felt I n results . But it is open to any mi n r or prospector in the Federated Mal ay S tates to send concentrates or other mineral samples to my office to be dealt w ith as quickly as oth e r w w e w t ork permits , hile such sp cimens as can not be dealt i h satisfactorily here are for“ arded to the D irector of the Im p eri al I n L w f e s I nstitute on don , hose sta f supplies analyses of the high t order an d also advises as to the treatment and disposal of mineral s of e conomic value .

P ROS P$ CT I N G D $ TR I TA L D$ POSIT S I N T$ $

GRAN I T$ $ I LLS .

We all know that natu re abhors a va cuu m . It might be added that next to a vacu u m nature abhors a defin ition; a n d this is n o less appare nt whe n any d etailed clas s ification of tin - Ore 15 I n e deposits attempted than oth r branches of scientific research . “ “ ” \V e k - b may tal glibly about alluvial and lode tin ore , ut ’ ’ since alluviummean s i n the strict sense of the term the a ebrzs s e l of rock sort d out in to gravel , sand , and c ay , by river action , and “ ” tin s lode ore should be confined to ore that occurs i n vein , it w il l be foun d that such a broad division does not in clude by h any means all t e types of deposits that are know n to us . S om e w 15 of e division , ho ever, necessary, for the sake clearness , and I hav the refore adopted on e that i s at the same time comprehensi v e and easily u nderstood . $ nder detrital deposits I incl ude a ll im mediate sources o f tin - ore where the cassiterite has b een deposited mechanically after removal from the position it originally occupied when it first came i nto being as crystallized w to tin dioxide , or here it can only be said have been moved from w e its original position ithout subsequen t deposition , as in the cas w f of soil deposits on the sides of hills , here movement is e fected by soil - creep ; while u nder n on - detrital deposits I i nclude al l de p osits I n which the tin : ore still occupies the same position in was l b mica i which it origina ly precipitated y che l act on . 4

’

- - . inc e all as as is k no wn S . has b d i d , tin ore , far p een er ve — u l tim ately from granitic m agmas that is masses of m olten m t s o lid ifi e d a s e s- I ro o s e . a erial that granite and alli d rock p to d eal first w ith th e detrital deposits that are fou nd resting on the parent rock in the granite hills .

A s lthough a large output of ore is derived from these deposit , they are l ittle known ow ing to their distance from settl ement s ' f s and the con sequent di ficulty of transport . They flourish mo t

- $ l u P $ l u S an d at the present time in ahang and elan gor , those “ whose business it is to visit them k n ow to o well that they exten d from the - l owest valleys near the gran ite margin up to the high divide where Chinese m iners S ometimes have to pay as m uch

. s 6 a $ per pikul tran sport to the nearest town .

The ore - won is mostly from the beds of stream s an d the l i V alluviu m fringing the steep sides of the v a eys . alleys such a s these are ge nerally ful l o f huge boulders o f gran ite that “ a e ar ~ to w - w pp be ater orn , but that are really hard core ” boulders of gran ite that have resisted . w eathering . The richest detrital ore is generally fou n d un der these boulders owing riffi e s to their having acted as natural , an d a comm on sight i n the gran ite hills is tw o o r three Chin ese coolies burrowing under

' vast m as se s o f gra n ite for p ayxd irt; tak ing great risks of letting d own upon them se lves tons of rock which are sometime s u s s s pported by a few stick of oft timber .

What guide is there to payable tin - deposits i n the granite hill s $ They are n ot confined to any particular z one and there : fore the field for search is a large o n e .

Th e b e st - guide is the presence of pebble s o f to urmal ine

b . earing rocks i n river , beds These may have travelled some

w - n m w distance do n stream , an d if a river contai ing the be follo ed

- it ‘ b e th at hi h e r u - l up , an d if fou nd g p stream the large bou ders n w o f of granite ”containing promine t hite porphyritic crystals w i felspar become fe er, givin g place to fin er grained gran it c c o ntainin to u rm al in e w rocks g , an d veined ith quartz , felspar , w hite m ic a tou rmalin e an d r , then a search should certainly be

- a . o f m ade for tin ore The presence tourmaline in qu ntity ,

w m . f o r ho ever , any gran ite stream i s sufficien t reason a search fo r o re w s d , but here collections of boulders such a those i ndicate

- f tin s . are ou nd , the richest ore deposit may be expected

If - - b d l a r e n. e . o r o th e sides of a valley i n a stream i g quan z

titie s of quartz are found , they probably indicate the presence of f a s w - o r vein , and search hould be made do n stream detrital ore

' P a w v . from the outcrop of the ein ure qu rtz alone , ho ever ,

w ith o u t to u rm al in e o r w e . hite mica , may l ad to n oth ing Of value I ndication s may be found also of complex veins containing iron -g s a n d s u s tif /a Oxid e pe rhap s some m e tal lic sulphides . The e j y s r n-S a w . imilar sea ch . do tre m i i The pre s ence of topaz ~ b e a ring I o cks is also a good gu id e fO i i to t n ore , but unfortun ately topaz s a difficult mineral detect w i tz he n in small gra ns , being very like quar in appearance (in min ing and prospecting Operation s its prese nce is g e n e I al ly u n noticed until an attempt is made to separate it from the tin ore) .

A I n r 1 5 wh o r gain , if the soil a g anite valley ite an d clayey , if the stream is found to be flo wing over white clay w i th grain s s tin t of quartz , and perhap tourmaline also , ore may be expec ed , w w t wa s the hite clay being kaolin , a m ineral hose forma ion con n e c te d w ith th e formation o f ti n - ore ; and if it is found that the w e o f hite clay is travers d by vein s quartz , quartz and tourmaline , w r w a quartz and hite mica , or qua tz , tou rmalin e and hite m ic , the chances of finding payable deposits of tin ore are increased . C o f I l l the ms l e v e s rystals cassiterite may be foun d ‘ the veins or in ’ the clay (m a e section I I ) .

' Owing to the Concent rating action o f rive rs and th e n atu ra l '

- 5 riffle s f e - th e ric lI e s t a forded by the big cor boulders , detrital e u d posits may be expected , generally speaking , in the all uvi m

' but detrital ti n - ore is also fou n d i n the soil Of the steep sides of w r fro m on the granite valleys , here it esults the disintegrati of n on

‘ ’ ' a m o u n t Of m e e m its o ri in a l detrital deposits , some ov m nt fro g

e f e - e a position having b en e f cted by soil cre p , that is , the grad u l e mov e men t of the soil towards th e bottom of the vall ys . S ince th e all uviu m w a s i n al l probability im mediately deriv e d from such tin w bearing soil as the stream s carved out their beds , he n ti n i l um o u nd s e S bear ng al uvi is f , the side of the vall y hould be prospected also .

W - l - s hen a ti n hearing val ey has been found , the next tep is to consider h o w to arrive at the value of the groun d . I n exceptional w of cases , such as here an alluvial flat is formed at the j u nction tw o w h e re a h as streams , or dimin utio n in the grade of a stream ht m a broug about the same result , a reliable figure y be obtain ed by pittin g (borin g would almost certai nly b e too m uch impeded o r S th by boulders ) . Close pitting trenching on the ides of e valley also w ould give an idea of the am ou n t of tin ore i n the i soil , but as the ore s likely to be very patchy a considerable

$ error could be avoided only by going to great expense . The ore i n the boulder - laden alluviu m at the bottom of the valleys is w the al ays patchy , and the fact that richest patches are generally co vered by huge masses of sol id rock m akes systematic p ros ' w e c tin . p g impossible I n fact , hen once it has been ascertained

- i e that tin ore is present in quantit es that are likely to be payabl , th e best m ethod o f getting further in formation is to fl ood the

a svith Ch o i w r On b . C v lley inese co l es o kin agD tri ute ircumstan ces might permit bringing water from a d is ta n c e by means Of a ditch S d o vs n to enable the tributers to luice the hill sides , an d after a ’ f e w months Work the lessee should be able to j udge vs h e th e r it w ould pay him to substitute a small hydraulic plan t for his tri b u ter5n An Obj ection to p utti ng tribu ters on to such land 15 that 6

“ i s - b t i l a nd l the they p ck out the eye of a ti n ea ng va ley . eave

. w w l poorer grou nd This may be so , but ithout their aid it ou d be difficul t i n this cou ntry to prove that a large n umber of ’’ eyes exist . I do not think that anyone who k nows m uch about the Chi nese mining cooly would expect good re s u lts from

ll d a - s d me n working a granite va ey on y wage , if he ever obtaine he e n s u s t m on ch term .

PROS P$ CT I N G N ON - D$ TRITAL T IN D $ POS I T S I T $ G R LL N $ A N IT$ $ I S .

$ n derlyi ng the tin - bearing soi l on the sides of the granite l l va leys , and u ndern eath the alluvium , the work of tribute coo ies o r ind ividual miners has someti m es disclosed the sou rce o f the detrital ore by un covering various n on - detrital deposits that have themselves yielded large quantities of ore . These are , fin e grained granitic ro cks w ith ti n - ore disseminated through the mass an d also occurrin g i n a n u mber of smal l vein s of pockets ; l arger quartz veins w ith bunches o f ore in big crystals ; lenticles z and veins of rock consisting of quart , tourmaline and cassiterite i a nd s rocks contai n ing t n ore , tou rmaline and topaz , sometime

in - t bearing veins traversing porphyritic granite .

For the mos t part the s e no n detrital deposits are so soft owing w s w to eathering , and another more ob cure cause , that the ork o n the alluvium or soil above 15 carried on down into the non detrital r deposits w ithout any b eak . The val ue of tribute work I n u ncover s s s ing the e deposit can not be gainsaid , but pro pecting such deposits by mean s of tribute labou r 15 hard to defend . A n alluvial or soil deposit is esse ntially a surface deposit that exte nds to a l w s imited and easily determ ined depth , herea it can n ot be stated that one of the s e n on - detrital deposits will certainly end at a give n

. S l depth ome of the s ma l vein s and masses of ore , it is true , s l I n are oon exhausted , but they are genera ly contained a rock

15 e - l wa w that its lf tin bearing , an d that may exten d a ong y do n i a nd i nto the granite mass , traversed by more small ve ns contain ing similar bunches of ore . The problem is to find out to w w b w a s hat depth it ill prove paya le to ork such rock s , and there is n o reason to suppo s e that in the course o f a descent i nto such grou nd rich and poor material will n ot

b e , alternate , it is n ot to expected that tribute labourers will w prospect it thoroughly , since hen they are faced by a mass of a to w e grou nd th t does not pay them ork , they suspend op ration s i n stead of carrying o n a search for more payable ore beyon d the . w poor groun d . A n example o f the drawbacks of such ork wa s occurred not long ago . A pipe of ore in gran ite discovered w and given to tributers to prospect . These me n orked steadily e i a nd l at the pipe , taking out very b t of ore rough y dressing it a s e s A wh ' l ong as it paid th m to do o . t last there came a day e n the o re dim in ished in val ue and vs o rk did n ot yield a p rofit The tributers stopped a nd the pipe w as regarded as of no f urther u s e w a s s , although there still ore in the face , an d no rea on to w suppos e that it a s hopeless to look for payable ore beyond .

w to s It ould , of course , be wrong advise m iner to spend large sums in s uch a proceeding as excavating absolutely barren rock o f w i n the hopes finding ore some here ahead of him , but as long as there I s n ot a marked change from rocks such as o ne usually w finds as sociated ith tin ore to hard porphyritic granite , an d as

i s - w long as there tin ore , hether i n payable quantities or n ot , w th e in the orking face , it is o nly taking ordinary risks that cann ot be elimi nated from prospecting and m in ing Operation s to ’ go ahead as far as one 5 availab le capital allows I n an attempt to fi nd bette r o re .

I shall deal w ith the subj ect of prospecting non - detrital w w deposits more fully in a l ater section , but ould add here ith regard to the finding of n on - detrital deposits i n the granite hills that it must be admitted that w ithou t the aid of tribute w ork on ’ w detrital deposits the prospector s task is on e that looks ell . nigh hopeless . Imagine a prospector from Australia or S outh Africa suddenly landed on a block of o n e thou sand a cres of virgin j u ngle on the S lopes of a gran ite mou ntain w ith instructions to h $ find o w m uch ti n o re it contained . nless a stream were in w o f . sight , perhaps not a vestige hard rock ould be visible N w othing but trees and more trees , u ndergro th and more u nder w o n t . N gro th , a floor of dead vege ation and sodden soil othing eve n suggestive of mineral w ealth ; no rocks to show him w - hether he w ill be l ikely to find tin ore o r n o t .

That s peculation is n o better a produ cer of tin ore than I a l prophecy is very true , and re lise as clear y as anyone that ultimately the prospector and m ine r prove the I I e al th of a mining i t field , but it is perhaps a legitimate digression to suggest that II ould be very remarkable if the enormous area o f granite that ' w e I n w II e - w have he re , and hich have al ready fou nd tin ore idely d - istributed , failed to yield many more non detrital deposits than

' II e f know o at present . I II ould recommend in this con n ection “ anyon e interested I n the subj ect to read The Geology o f the

VVa te rb e r - a Ge o l o g Tin Fields ( Memoir N o . 4 of the Tran sv al

ic l S . V . . a 0 . . P v 1 $ $ . g ur ey , 9 9, by H ynaston , T Mellor , and S w b o o f in rne ) a volum e. that w ill give a very clear idea e S A n on detrital d posits of tin ore found in outh frica , an d the s pos ibilities of similar deposits elsewhere .

“ PRO S PECT I N G A LON G GR AN I TE MAR GI N S .

p e rie nc e in other countries has sho u II that the greate s t nu mber of tin deposits a re found near the j u n ctio n of the pare n t a e w w h n in gr n it ith the rocks i nto hic it has been i truded , both and la t o n d the former in the ter , an d the whole the evi ence in 8

n t . this; cou ntry d oes o point to any marked exception to the ru l e . ’ A w h at s o w re t first sight , ho ever , the fact t many orkings a

I II s - t located high up the granite hills , almo t equi dis ant from w i e either m argin , ith m l s of gran ite on either sid e , se em s to con s titu te a formidable obj ection to accepting as a gen eral rule the s t atement that tin depo s its are m ostly confi n e d to the neigh d . w bourhoo of gran ite j unction s ith the older rocks , but there is - some r e ason to suppose that the p resent form of the ma m granite range o f the Pe ninsula is n ot very differen t from the original form of the mass o f granite that solidified deep in ’ D t o f th e earth s Crust . enuda ion has removed most the altered s a t o n o f rock th t then res ed the top the solidified igneous rock , w th e s o h a t but has not eaten far do n into ign eou s rock itself, t u w e may be j ustified in rega rding the w hole superficial area of ' th e main granite ra n ge and othe r gran ite ranges a s being a p p ro xi e a t mately the out r limit of the original gran ite m ss , i n addi ion to the actual j u nction expos e d o n the flanks o f the mou ntains .

We w c o n s id e I w t ill here , ho ever , only the actual j unc ion that w e can see b o tII ee n the granite and the o l d eI rock s on the flanks of th e big hills the contac ts w hich many look upon as the most hopeful plac e s toI d is c 0 I c rie s of rich m e .

we l l th e a w This belief i s fou nded , but m in point that I ould make i n this section is that one c a nnot expect the w hole line of

- contact or its neighbou rhood to be stan niferous . A prospecto r w orks along the edge of a certain outcrop of granite and fi nds w w n o f nothing orth orking . He may co clud e that the theory a

- granite contact being a good place to look for tin ore is incorrect , and one can not help sympathising w ith his bad fortu ne . But the theory is not to blame ; the prospector has bee n hand icapped in n ot e w to o f b ing able , o in g the force circumstances , to extend

f o f . his operation over a su ficient length the con tact In deed , if w e m a tte r w h o w f consider the from another point of vie , ortunate it is that the available tin in a mass of molten granite h as n ot been evenly distributed ove r the w hole superficial area of the w solid rock . Had that been the case the deman d for tin ould have to be perhaps eve n greater than for gold or platin u m to make it w orth w in ning . Tin deposits can not reasonably be expected along the w hole o i a n to i s of f a gra n te margin . Is there y guide those port on the 3 margin that are stan n iferous .

There are N o possi b ilities . the occurrence of mi nerals that i generally accompany t n guiding one to the ore itself , and the possibility o f some p a t tic u l a r rock havin g favou red the precipita tion o f ti n d ioxide i n quantity more than other ro cks along

the margin .

A o f I n s in the case tin deposits the gran ite hills , the o f I s w I n occurrence tourmal in e an invaluable guide , hether it be t e I b d h granite mass o r i n the al tered o lde r rock s . t wil l e foun 9

e a nd r s I n i g nerally as large easily ecognisable cry tals the gran te . but in the altered sedimentary rock s it w ill rarely form good w crystal s and in con sequence it ill be hard to detect . The commonest form I n w hich it occurs is as tourmaline c w s h ist , a rock that looks rather like chocolate he n slightly w w w eathered , and he n fresh is fairly hard ith a peculiar lustre due to light being reflected from thousan d s o f microscopic prism s o n o f b rown tou rmaline . The presence of this rock the border o f the gran ite i s very p ro m .s in g and search should be made I n

al l streams draining the coun try w here it occurs for ti n ore .

Abundant qu a rtz n e ar the g ran ite margin may mean the o f presence of a vein carrying tin , but u nless traces tourmali ne , w hite mica , or m etallic sulphides can be seen in the quartz , it may fail to lead to anything o f value A feature of veins containing tin ore in the altered rocks beyond the granite h margin is that t e y rarely carry m uch quartz .

I n some cou n tries abundan t I ron oxides I n rocks such as we g et here adj oining th e granite would be a hopeful sign o f the

- - - presence of a non detrital ore deposit , but here iron ston e w laterite is formed so abundantly in eathered schists , shales ,

and sandy rocks , and the limestone so freque ntly contains in its e rough cran nies and aves masses of deep red ferruginous earth , both o f which have n o im mediate con nection w ith th e tin deposit s n as far as thei r formation is concer ed , that they alone can not be I f v . w taken as a guide , ho e er , on breaking open a hard mass of

w - bro n iron stone , a core of bright metallic iron sulphide is found , then the iron - ston e may be taken as indicating the presence of a

- n o n detrital deposit in the vicinity , and search should be made

fo r - w l o f tin ore , si nce the sulphide shows that the ho e the oxide , s h o f probably , has been derived from ulp ide form ing part a lode

or mass of ore .

in I b ut Topaz is not very likely to occur the altered ocks ,

may occur abundantly in the granite near the margin , and is a

guide to tin ore .

It is important to not e that tourmalin e is v e rI rare i n o n non detrital deposits contain ed i n limestone , but that the

0 1 - other hand pale green colourless fl uor spar is com mon . S I a ulphides of ron , copper , and arsenic are l ays abundant , and s II tibnite sometimes occurs ith tin ore in limestone , so that if any of these minerals a re found I n limestone at the contact with the

a - o f o r . granite , they prob bly indicate a deposit tin e

With regard to the question of o n e I o c k along the granite faI o u rin margin g the deposition of cassiterite more than an other, I s to b e a a s e I there little s id . I h ve en evidence o f tin ore l I a ing bee n form e d i n g I e ate r qu a nti ty in s a d dy than in finer grained I I a n n e t s a a t h rocks , and although y th t this should b e re g a r d as ’ mil e II iII c lin ed 10 a I o a tt t t io n t a n o t o the , I ould be | m re n o u cr p of sandy rock s abutting on gran ite than on s hale s o r sl ates I O

’ 1 e s hav e j t menti o ned certai n m ine rals that m ay act ; as

u I d e s to - g tin deposits i n l imestone , but ghe j unction of the l ime stone w ith the granite is remarkable in almost every case that I have seen in being clean an d in the limestone con taining n o

. ore deposits of importance . S ometimes indeed the lime s tone at the j unction appears not to diff er at all from the limestone far w w ’ f a ay from the granite margin , an d it ould be di ficult , as far as tO ‘ fi nd my experience goes , a less promising rock adj oining the n o t g ranite than the crystallin e limestone . The same does apply , w w th e ho ever, to the granite margin at its j unction ith limestone , n o r , of course , does it apply to detrital deposits lying i n cavities formed i n th e l im e s to n e by solution : the statemen t refers solely

- to non detrital deposits .

A possible obj ection to the limestone being regarded as u nlikely grou n d fo r tin - dep osits is that tw o o f the m ost fam ous

‘ mi nes in the cou ntry are situated on or near the j unction o f l im e w o S e stone ith gran ite namely , Tron h and ung i Besi ; but as far as I kn o w at present in neither case has the output of ore com e from the limeston e itself , n or have I ever seen any ore actually w . \Ve w i n the limestone at either m ine kn o , ho ever that ti n o re e doe s occu r in limestone , ge nerally i n pipes or v ry small n o w vein s , and although those fou nd u p till have been a con s id e rab l e distance from the granite j unction as seen on the s urface , there is good reason to believe that they are conn ected w o w e o w n ith granite i n depth , an d theref re must that similar de posits may be found at the j u nction seen on the surface of th e

‘ to e n c o u ra e ground . But pipes and vein s sufficien tly attractive g

- b e exploitation have proved to rare , and their existence - does n o t affect the general stateme nt that limeston e adj oining a granite margin is no t good groun d for prospecting for n on - detrital $ w W l l l deposits . o w different is the case ith detrital deposits be seen in the next section .

PRO S PECT I N G A L L$ V I A L FLAT S AN D ALL $ V I $ M

IN T$ $ L I ME STO N E $ I LLS .

I n a typical al l uvial deposit nature has greatly assisted the m etal l I c s u l h I d e s a II d tw o w : p , miner i n ays first by oxidizin g the ‘ again by a d istinct sorting of the material in to gravel , sand , and c o n c e ntratI o n o f ; clay . The former facilitates the the ore the ” ‘ “ latter results in the deposits bei n g more regular than other t r l s d eposits ; so that when there is n o doubt that the p ro sp e c o o dealing w ith a real alluvial deposit formed by a rIv e r I n I ts s b e d - valley , an d when bore have been put down to rock at w a ro x1m ate l intervals in a geometric pattern , sho ing an pp y

- - b e con stant thickn ess of tin bearing grou nd , the n it may assumed that there is a bed of pay - dirt w aiting to be w orked of the same

d ist b u te d . extent as the area over which the bores have been n l l :

“

Now e e s n ot - b e xh d as th s note do preten d to e austive , a n in

u n o t ' b e o u r'k n o wl e d e o f th ' fact co ld so , seeing that as yet g f e

structure of the cou ntry is on ly j ust com mencing to crystallize , I propose to limit the remarks on al luvia l flats to a brief dis c u s io n s loo n . of that familiar term y Moreover, elaborate n otes o n the prospecting of al l uvial fl ats might n o w be con s idere d w some hat late .

A t first sight it wou ld appear that the re are no difficulties “ ” w m m mi f an hidde n by this ord , an d that / g is a phrase that o f ‘ admits no misapplication . Nevertheless it is w el l know n to

- some that in actual . practice len does n o t mean bed rock so much as an arbitrary down w ard limit to the pay - dirt fixed by . C us e the u ncritical but pious opinion , although the hinese of “ term is certainly more dign ified than th e analogous s a mpd z ” d a d a Mal a o ld - P wh o r p of the digg er in ahan g , is ve y ron e y ’ g “ ’ ' ’ ’ to cry s zz a a /z s a mp a z a a a a w he n w orki n g for someone else if

“ ' the ' particular pit he is engaged on become s too deep or too w e t for his com fort .

What the real s igni ficance of t o ng may be to a Chine s e

1 w . w e miner do n ot profess to kno It has , ho ever , b en taken by ” w ’ - w hite miners to be the equivalent of bed rock , hich suggests

- some hard rock on w hich the alluvial deposits lie . If bed rock w w in th is o f ere al ays hard cou ntry , the proble m determ ining w t w he her on e had arrived there or not ould be simple , but n ot only is it difficul t sometimes to decide w hen the bottom of the ' s o m n alluviu m has been reached , but meti es one s preco ceived . notion s are upset by finding that there is more than on e b ed of

- h o w - pay dirt . S ome suggestions therefore of variou s bed rocks w . f in this cou ntry may be recognized ill perhaps prove o value .

I t is assumed that either bores or pits are used for prospecting .

— s This is usually easily recogni ed , but som e e w r f tim s , whe n much eathe ed , it looks rather like inely granular quartz . If after heating fragments i n dilute hydrochloric acid no

x is iv e n . gas g off, then the rock is likely to be quartz If the rock ff w n on ly e ervesces in dilute hydrochloric acid he heated , it pro bably co ntains a lot of m ag n e s I u m ( magnesium limestone) or

i - iron (chalybite) . It is not uncommon to f nd a cap of iron ston e and mangan ese oxide s im mediately above the limeston e . It should be borne very carefully in mi nd that where lime ston e forms the bed - rock to alluvial deposit s they may prove to o ri inal o s itio n o f be much disturbed, from their g p by reason the f gradual an d irregular solution o the limeston e un derneath .

' — - /m l es S l a tes a nd S c/z zs ts w ll a S , . These i be soft for few , inches o r perbaI 5 feet u nder the l ow est bed of al luvium and it

- b i n is possible that han d boring tools may e driven . some d sta ce ' ' i ' a s k Th e u r o s . do w n into them to n o p p e before h rd rock is truc . l m s d rz f o m th r w l l . éb r r p bo es , however , i a wa s contain frag en t e ; y 1 2 show ing the of iginal structu re of the rock s and there shoul d be no difficulty in determining w hether the last bed of all uviu m has 0 been passed .

‘ ' — Q u m z z z te a n d S a n d s to n e . The same applies to these rocks as to the last mentioned . A ngul ar pieces of stone that w w z have resisted eatherin g are sure to be found ith the d é br s .

‘ ’ — Gm n z z e a n d A l l z ea R ocks Many alluvial deposits are o n

- w to a granitic bed rock , an d o ing the extraordinary man ner in w hich gran itic rocks w eather in this cou ntry it is often very n hard to tell if o e has passed o u t of alluviu m or n o t . I n som e ca s es so great is the resemblance betw een a w eathered gran itic rock an d a detrital bed that the only satisfactory test is the

o r . w presence absence of vein s I n granite , ho ever soft it may be w o n e w t from eathering , nearly al ays finds distinct vein s of quar z . W etc . I n recent alluviu m veins neve r occur . hen one .boring may pen etrate a long way i nto decomposed gran ite w ithou t w o f k no ing it , but as there are good chances the rock being stan niferous , it is n ot altogether lost labou r , but if for any reason it is found necessary to determin e accurate ly when granite l w a w is e ntered , the on y sure y ould appear to be to prospect by s w w a n mean of pits , hich ould enable the p rospector to see y veins in section .

S ome o f the early literature deal ing w ith o u r tin deposits l eaI ko n I s o f e u es the idea that the g generally a mass kaolin ( g , ’ “ ” f P L O re D . o hillips an d ouis eposits , pp 599, This , w a s e o n ffic course , a gen ralisation fou nded in su ient observation , but kaolin u ndoubtedly does occur as bed - rock and should form a n exception to w hat has been said above about a bed rock o f o r gran ite allied rocks , si nce the extreme fineness and the w hiteness o f the clayey mass render it easily recognisabl e . $ aolin i s frequently stan niferous and therefore bores or pits should be pushed o n through it until hard rock 15 reached . ” — - R o u Cl Bed ck of S fi ay . I n addition to the rocks men tio ne d ab o I e it w ill be fou n d I n som e parts o f the coun try that

- f l s w below the pay dirt sti f c ay I encou ntered . There ill be more to say of this in the next section ; here it w ill suffice to remark that although the clay m ay be barren im mediately u nder the p ay o n dirt , bores should be pushed through it until they can go no I I h I c h w e n farther , ill probably be d ue to l imeston e bein g cou ntered .

AL L$ V I $ M I N T $ $ L IM $ STO N $ $ I LL S . The origin of o u r limestone hills is a matter that has give n l much food for thought and ca led forth some original ideas . I do o w n w o n not propose to give my vie s the subj ect in detail here , t a and must herefore hope to be p rdon e d for a ppearing dogmatic . w a re $ t V The best k no n limestone hills those in the in a alley , and if anyone w ill look carefully a t their sides he w ill see n ear ‘ the base o f many cliff s n um ero us cle a rly marked horizontal w $ gro o v e s f The s e get fainter higher u p the cliff o ing to th e ir

1 3 having been formed long before those low er dow n and a c o n s e to w t o f quent longer exposure ea hering an d ( the formation se t o con dary calcium carbonate , agencies that have led their complete obliteration at a height of about 8 0 feet .

N O I I these grooves w ere c u t in the limeston e by I u n n ing water and are con clusive proof that once the level o f the $ inta V w a s i n o w w a s e alley higher than it s It once , I believe , l vel w t o f r o f i h the top the highest lim estone hills , and the structu e w the valley w a s then more or less as show n in Figure I . It ill be seen that the lim estone mass w hich n o w forms hills stood up ' i n the earth s crust as though it w a s intended to be the t foun dation of some titanic building . The ver ical faces , due t f a i i i a n ite o aulting , were fl nked by t n bear ng g on the east an d by stan n iferous clays a nd by sch ists that may also have been tin f s w . l h e s o bearing , on the est relative thick ne s clay an d schi ts at that time is not known .

A s the streams o f the $ inta Valley cut dow n into their beds

' r and meandered ove the plains they formed , keeping to the more w i easily den uded clay s and schists , they ould from time to t me e a t w a ru n alongside and into the limestone lls , thus makin g the A n w horizontal grooves . t the same time sol utio by surface ater w l i w c ave s ou d be act ng on the limesto ne , hon eycombing it ith ;

- an d the streams w ould be flow ing o v er ti n bearing grou nd .

G - w ravel , sand , and silt , therefore , all carrying ti n ore , ould be w I I w ashed d uring times of flood , and perhaps he n the stream s ere n i c m e s m w ormal , nto the and crevices of the li estone and ould II be left th ere while the stream san k lo wer a nd low er . I course of t ime the first formed cave deposits w ould become d isturbed by further solution of the limeston e and their arrangement in layers

o f d . w i n a . gravel , san , etc , ould som e c ses be largely upset w s Moreover , most of the deposits ou ld become deeply tained by iron oxides and some wo uld be converted into a hard mass by

w s o a - calcite form e d bet een the grain s , th t the tin ore could not be w o n u nless the ston e w ere crushed i n a battery .

If anyone w ill consider the sequence o f events as give n above w e w and ill accept the stat ments ithout requiring all the evidence ,

- w . I w w hich , may say . is based on ell kn o n natural processes , and

' e - w $ do s not invoke the aid of pre Hutton ian theories , he ill see that

'

- wherever . limestone hills - are flanked by tin bearing beds they Should be searched from to p to b o tto m for old alluvial deposits formed as the streams carved out their valleys , but I can not say w that I k no of any guide to s uch deposits in the hills them sel v es . Ol d chan n els by w hich mas s es of alluvium w ere w a s hed i n may e have bee n blocked up by recent d posits of carbonate of lime , an d the alluviu m itself m ay have been moved from its first position w n to u R o i g sol tion of the limeston e . eason tells us that valuable

it . deposits may occur on the very summ s of the limestone hills , i n but there s n o short road to fi ndi g them . diligen t search o r good fortu ne al one can s ucceed I 4

P RO S PECT I NG DET R ITA L DEPO S I T S BE LO W T$ $ R ECE N T A L L$ V I $ M .

the For most part detrital deposits , or , as they are som etime s — to called , placers , are of recen t origin that is say , although they o l d may be thousands of years , they belong to the same period w w e w of earth history as that i n hich live . There are , ho ever , certain older detrital deposits that have bee n preserved from a A former geological period , such as the deep leads of ustralia , from

‘ w w o n hich ore can be , an d i n this cou n try there are certain w stan n iferous clayey beds , sometimes ith included boulders , that are n o t on ly older than and distinct from the recent detrital

e - l d posits , but are older than the tin bearing gran ite so fami iar e in ou r hills . A s yet very little is k n own of the extent of th se o ld detrital deposits , but they may be expected to occur immediately above limeston e , an d they may be separated from recent depo s its above by schists or sandy beds . The clays referred to in the l ast section as being a possible t o ng are the s e clays .

The problem is the prospecting of beds of cl ay c o ntaI n I ng

- - d b c o v e re . tin ore , lying on a limestone bed rock an d maybe y younger rocks themselves p robably stan n iferous . First let m e o f indicate some of the peculiarities these beds , both inherent and

u th - ffi u d e to e nature of the bed rock , i n orde r that the di c lties w likely to be met ith may be appreciated .

I n an alluvial deposit the s orting action of run ning water has resulted in the formation of strata o f pay - dirt of approximately two w s even value , and if bores , put do n a chain apart on the ame w i stratum , both sho f ve katis per cubic yard as the value of , the grou nd , it is a reasonable deduction that the portion of the bed lying betw ee n the tw o bores carries five katis pe r cubic yard al so . $ xperience of the o l d clay detrital beds show s that in their ca s e s w w uch a deduction ould be e ntirely u n arranted , because the mode of formation of the s e beds w a s such that little or n o sorting actio n took place ; an d although in the locality w here they are — — b est k nown so far Gopeng every s ample taken yield s some

- s tin ore , sometimes , it is true , n o more than a trace , the ca siterite is so irregularly distributed throughout the m ass that a large ' ' error may creep i nto prospecting w ork by bores u nl e s s a great e n n umber are put dow n . As an instance of this I may m ntio o n e particular case w here a mine manager had put dow n . w a s n um erous bores and obtain ed poor results . The mine w w ro u nd ro s e c te d orking , ho ever, an d i n course of time the g p p

w w . t . was cut a ay an d ash e d I gave quite a good return , the explanation u n doubtedly bei ng that the body of the Cl ay contained o re b u t l m l l a very s mal l amoun t of , , also he d s a patches of rich e s t g rou nd that had all been mis s ed i n the bore s . The actual r ul ' t t mi h s wa s a r i n nI aII a e r . b u i i n thi case prob bly g atify g to the g , g tJ

1 6

' ' ' ‘ ‘ ‘ thick nes s f ove rb u rd e n a nd the fifth W uld s fo uI a great w , o how

“ ' - e h . d feet o f pay dirt at a m o d e rate pt .

i ’ ’ What w ould be the prospector s report on the p ro p e rtyi Th is hypo thetical case sh ows h o w far a prospector could go astray with a single continuous bed of pay - dirt lying im m e d i ,

- $ ately on the bed rock . o w much greater would be the d iffi

‘ c u l tie s if in s tead of a simpl e layer of p ay- dirt there w ere above the l im esto ne a thi c k mass of clay w ith irregularly shaped bodies o f ' '

‘ - l l pay d irt s p o ra d ic a y distributed in it . A s the clay fell into

- - rm o re - w n the cavities fo ed by solution , the bodies ould be d raw n i a o r T out i nto l o g vert c l in clined streaks . hey w ould n ot ne ce ssarily be n ext the l im e sto n the base of the cl ay m ight be w q uite barren . Bores put d o n i n such grou nd would sho w the

~ O n e in o s t . e rratic results . rich bore might be surrou nded by

- a bores th at yielded n o tin ore t all . Bores passing along vertical

‘ s treak s o f ore w ould produce the impression that a bed of pay - dirt w f w of great thick n ess had been found . Bores put do n a e feet aw ay from these vertical streaks might show n othing but w orthless

w - w I grou nd . It is but too ell k no n that lan d such as attempt to h a s e w e describe been open d u p ith great expectations , d stined l l to be dispe led , and although it is only human nature to fin d fau t f h o w With the prosp ecting in such cases , it is di ficult to see it is u C possibl e nder the circumstances to blame anyon e . onsider that hitherto the prospector had been accustomed to valuin g orderly alluvial deposits by a simple calculation that had always ” proved approxim ately correct . He takes the same tool s a little w i deeper , and not u n n aturally applies the same calculation s , th the result that he proves to be entirely w rong . The pros pector ’ o nly h a s h is o w n and other people s experience to guide him and

' iin til cert a in mines w ere Opened up in the Federated Malay “ S I w o f tates , n o on e , as far as am a are , had had experience a

a - , horizo ntal, bed of p y dirt being suddenly replaced in grou nd that m ight excusably be taken to be a contin uation of th e f t o . alluvium , by ver ical strips the sam e ore I

’ Seeing that it is probable that the future output w ill d epend l l a o f is arge y on clays such as these , the v l uation the grou nd a m atter of gre at imp o rta II c e ; - but it m ust b e apparent t hat an approximately accurate figure can on ly b e obtained by. very c lose ~ w a w boring; hich means large outlay , but ould be decidedly w bette r than opening a m i ne and having to revalue it after ards .

“ Another pecul iarity o f these old detrital beds is that in so m e

' places th e y ha v e acquired a second supply o f tin - ore from the younger granite , resulting in very rich ground . The original supply - is detrital an d w a s produced mechanically ; the l a ter

- supply is n on detrital and w a s produced chemica lly . Littl e is o a re o f - kn wn about such occurrences as yet , but they course m ore

‘ likely to be fou nd near the j u nction o f the clay b e ds w ith t he

' r it a n d - e e g a n e in the vicinity o f vein s from the granite . Th r is

‘ some re a s on to ‘ s u pp o s e that the colour of the clay s may prove a ’ guide to s u ch deposit s , s ince in th e m e ighb o u rh o o d of ‘ vein s an d at l n re d so the gran ite j u nction they are gen era ly stai ed a deep , that one would be tem pted to explore more thoroughly where deep red clays reached the surface than el sewhere

- V PRO S PECTING E I N S AND P I PES .

’ The ease with which the d e trital tin - ore I n th e Fe d erate d ' M alay S tates has been w o n and the small ou tlay of c a pital m a h a d t a formerly n ecessary for opening a profitable ine , h ve marked eff ect o n the attitude o f the min ing commu nity towards “ ” in s an d prospecting and developing lode t . That vein pipe s I n m I exist , the latter the limestone an d the gran ite , the for er n s w limeston e , granite , and the ol d sedimentary rock , is k no n ; but while opportunities present themselves for obtaining quick return s from more easily II o rk e d deposits it is not to be expected w l ” that ill be employed to face .the risks of ode m in ing , ”capital n or is i t likely that everyone engaged I n the industry appreciates fully the great diff erence there i s between the exploiting of an alluvial deposit a nd the prospecting and development of a vein .

It is n ot intended i n th e presen t sectio n to attempt any discussion on h OI I a l ode should be developed that being entirely ’ w a a m iner s ork , but rece nt events in more than one loc lity have show n that a fe w w ords on the prel iminary stages of prospecting w e ill not be out of plac .

The great poin t to be borne I n m I n d when attacking a lode i e is that prospect ng methods applicable to d trital deposits are not , a l d l b e gener l y speaking , applicable to lo es , an d it should a so d ic remembered that u nless there are surface in ations to start o n , or some very good reason for expecti ng a l o d e in depth where there are n o Surface indications ( I do n ot attempt to defin e what a such reason s might be) , making holes in the grou nd in se rch of l l odes is very m uch like looking for a needle i n a bund e of hay ,

' with the important difference that you have n o gu a ra nte e that h e l l t need e is there at al .

The first asset a prospector sho uld acquire before attempt s m o wl o f o t n g to , prospect a l de is som e kno edge the c n s itutio of

$ l r i . lodes , an d particu arly of the dist ibution of ore n a lod e If this k n ow ledge has bee n obtained he w ill certainly prosp ect his l e I e l s l s particular vein by sinking a shaft and driving a ong it , thu preparing the way for systematic developmen t . But the man w ho only k n O II s the I I ays of certain d etrital deposits w ill r th e e s w assu edly obj ect to exp n se of inking an d driving, and ill perhaps argue that dril lin g holes fro m the surface t hrough the w $ A w lode ill answer j u st as w ell . s hand boring tools ith aug er m w w and sand pu p ould be unable to do the ork in most cases , r u he uses the best in st ument for the p u rpose , a diamond drill ; b t 8

' ' ' ' as h e Obj ec ts to the expen s e of sinking a n d d riving h e will hmit h i s l l - imself to a m ach ne giving a ma core , at the most two inche s i n i d ameter . i 3 w 0 O n the one S I d e the prospector h as h I s d l ‘ l ll a nd an outcrop as assets ; on the other side are several item s to be take n into con s ideration a s liabilities .

He w ill n ot realis e that the o utcrop of a l ode I s generally ri h r ha n c e t the ston e u ndergrou nd .

“ I n th e most regular lodes th e o re occurs in shoots that m l w are ostly i nc ined a ay from the vertical . O u r p rospector d oes n o t ' k no w w hethe r the o re u n d er ‘ him occurs in a shoot o r ' n o t a nd if he did kn ow he w ould still beignorant of the direction; k .it too .

L s f h u o o m e n s . o e o . odes are not continu ou sheets . g ore To “ - « quote Phillips an d Louis agai n ( p . I II a vast maj ority o f o f o r w cases the more metalliferous parts a lode , those hich yield e the ore sought in an approximately marketable state , constitut c o m aritiv e l a n b f . w e w but a p y small proportio n of the hole , d ut metalliferous vei ns a re sufficientl y rich throughout their exte nt to w a . M p y for the removal Of the hole of the veinston e oreover , sometime s it i s difficult enough to follow a l ode i n a level

' me as u rin s ix e o n o ut g fe t by four, accoun t of its pinching for a

a o r o re - gre ter less distance and then Open ing out into an body. aga in f The prospector can only make small holes in the rocks a little over tw o inches in d iameter an d he w ill hope to d e ter m ine by their help whether the vein is w orth m in ing or not . Let u s suppose that the outcrop is ru nning n orth an d south an d t hat w ork on the surface has show n the lode to be dippin g e ast . ‘ o u tc rO n d ‘ the The d rill is in stalled on the east side of the p a , e Operation s com me nce , the prospector calculating from the degre ‘ ‘ A 2 d i o . t .

. sixty feet the of , p to strike the l de at sixty feet

’

w u a rtz in d e e d . i s , , nch core ho s no ore n o q ' n othing remarkable is e a nd The drill pu sh d on , but still nothing is fou nd , the; i prospec tor concludes that the lode has pin ched out al to ' w h a s re a ll h gether , although hat . y appened is that the drill has passed through a barren spot i n a vein that would perhap s

w . .O n prove payable when orked the other hand , the drill m ight

‘

s . a nd . pas through a particularly rich spot , bring u p a core “ - o . o re w w e . c nsistin g of n othing but tin , hich ould make the lod

‘ $ app ea r a great de al more valuable than w a s really the case ; The core s from the small drill - holes w o u l d a l m o st certainly prov e: to be m isl eading as regards the value of the vein .

A n other thing t hat the prospector w ould be ‘ unlikely to learn from his drill w ou ld be whether th e l o d e w ere faulted or n ot ,

an u n fa u lte d , but given . lode and a distinct shoot of ore I trust

“ th e ab ove Will suffice to show that - a p rospector Operating from ' l the s u rfac e ' w ith a diamon d d rill cann ot e xpect reliabl e in forma t ion . 1 9

‘ r are cas e s h o w ev e r l l The e some , , in which a dril wou d prove

‘ s — a n u mb e r v ery u eful namely , in grou nd traversed by of small

’ V ' vein s close together . ery little reliance could be placed on the u ti t w values Obtai ned from the cores , but the lj y ould lie in proving the extent of the veins .

’ A o I V I n l pipe i n lim estone r gran ite , g g a small surface on y w to ork on , and being probably irregular both i n shape an d e to b y cou rs , is extremely hard prospect any method ; in fact the l i w w w on y thing to do s to follo the ore herever it goes , hich w ill gene rally mean that the pipe is w orked o u t as it is followed I II w up , a proceedin g that hardly fits ith ordinary ideas of pros e c tin R w w p g . eal prospecting , ho ever , ill be accomplished by n ot th row ing up the w ork w hen the ore becomes u npayable and w i n pushing for ard steadily as lon g as there is ore in the face , o r u - rocks or mi nerals , such as s lphides and fluor spar i n lime s o s s ib ilit o f tone , and tourmalin e i n gran ite , that indicate a p y '

- more tin ore exi sting beyond .

— o f The same thing applies to vein s namely , the necessity persevering although the o re visible at the m oment may not be l an d a ab e . P y , and even though the vein may disappear hillips ouis say on this subj ect S tatements relative to the entire disappearance o f lodes I II depth in ust therefore be received w i II o rk e ith caution , s nce , had the been continued , the v in w ould have p I o b ably have again been fou nd and hav e agai n ” become productive . I V I .

VA L$ AT I O N OF P R O S PECTIN G SA M PL$ S. ”

PR O SP$ CTIN G R $ CO RDS .

Leaving out of consideration beds of alluvia l tin - o re I n Open l l w o f a , m va eys here some regularity val ue y $ be expected but which have been I I o rk e d over already I n the better know n part s S o f of these tates , the initial source error i n calculating the amou nt o f ore in a given piece of land 18 that the pay - dirt Is n ot

. f w is evenly distributed This source of error , given e ficient ork , t doubtless the m ost serious Of all , and can only be coun eracted w h o w by close boring, but enough has bee n said to sho careful , one should be I n draw ing conclusion s from the distribution of ore as it appears in the bores an d I w o u l d pass o n to other sources of a o f o f error th t admit easier correction , especially the treatment a l the s mp es afte r they have been taken from the bores .

w o rk ' a im in I n all prospecting g at an approach $ to accuracy th e u o f the groun d taken from bore is measured , the sual system m easurem e nt being to pack it into a box o f kn ow n cubic capacity ' s u , Boxes of variou dimen sion s are used and , ntil lately they were ‘ ’ v wa s s u e s te d b all , I belie e , dry boxes , but last year it gg y

. G . . L A Bru s e h r M r ttenborough , manager of the Hyd aulic Ti n b M in es , that the u navoida le error due to the practical impossibility o f p acking the earth int o a d ry box so tightly as to occupy th e g o

' ’ ' sa me f sp ac e that it o c t u pie d before b e ing d is tu rb e d by the boring “ tools , could to a large extent be obviated by using a d isplace i wl ic h w s ment box in packing the earth ould be u nn eces ary . The principle of this box is delightfully simple and ha s the great advantage o f almost completely e l im ina‘in g the human element;

’ S e i - a u ppos that it is requ red to measure one qu rter of a . cubic b o w foot of grou nd . A xis constructed hose internal dimension s give a c u b ic capacity o f double the amoun t of earth required

n - o e half a cubic foot . The box is then placed o n a level piece of

- fi - w w grou nd n ear the bore hole and lled half full ith ater . The mat e rial to be sampled is then dropped into the box u ntil the w w w w ater rises level ith the rim , he n there ill be in the box exactly o ne - quarter O f a cubic foot O f ea rth p l u s the amount O f m oistu re it contained when taken from the bore .

‘ I t has been obj ected that when boring i n sandy g ro u n d t h e amou nt of moisture that percolates into a bore hole w ould make the ground sampl ed w etter than it w ould be in a w orking face; and that therefore the results obtained by a displacem en t box w oul d be subj ected to a considerable err o r . There are tw o replies to this : the same Obj ection affects dry boxes ; and it can be partially cou nterac te d by straining the san d in a cloth before

. w f measuring it I t mu st be admitted , ho ever, that the di ference between the moisture in the box an d the am oun t o f moisture that would be found i n a w orking face is a source o f error even w b o x n o t o ith a displacemen t , but that need preven t one fr m accepting the displacement box as bringing one nearer to a ccu racy than any dry b

The question o f the meas urement of earth in the loo s e so as to e nabl e a valuation figure to be given for the same grou nd

a I) . . e was w s 1 1 0 . b fore it cut attacked in 9 by M r H Bann erman , the author of a detailed paper o n the subj ect read before the Perak Chamber of M ines ; and l have had the advantage of d is cuss ing w ith M r . Ban nerman the difficultie s and sources of error. f rOu n met w ith i n boring . The d i ficulties of measurin g san dy g d . a b al l that rises in the pipes are dm itted , but taking a core out y ' O n of stiff clay w ith an auger look s a simple affair . comparing w w a s f t e w a s n otes , ho ever , it ou nd tha th re room for error even i n the recogn i t ion o f what belonged to the core an d w hat did not . The actual example that gave rise to m isgivings w a s as follows ’ I n certain bores in stiff clay I wa s employing a 5- i nch hand b i s e t o n e - fo Ot or ng , and measured my samples as sixth of a cubic

- n - each . The clay auger cut approximately o e sixth of a cubic o w foot every tw o feet that it cut i n depth . N it is com monly s u p o s e d that the diameter of the core i n a case l ike this would e te rm in e d o f tw o be by the in sid e diameter the pipe , and feet of 5$ inch pipe have a cubic c a pacit y Of cubic i nches, ’

- W whereas one sixth of a cubic foot is 2 8 8 cubic inches . hat ' becom e s o f the balance o f cubic i nches $ - To -me it seems that the solution is that the auger and not the pipe det er s d ia m e te r o f the a n d ~ tha t mine the core , as the former m ust have 2 1

' a o f an er free pl y inside the latter , the internal diameter the g is S con siderabl y less than five inches . uppose it is fou r inches

- 8 . , two feet of 4 inch pipe is 30 1 . 5 cubic inches one sixth of a cubic

15 2 8 8 e . . foot cubic foot , nearly the sam figure M r Ban n erman b al aIic e 18 thought that the of cubic inches . accou nted for by the bottom pipe compressing and pushing o u tII ard s the clay as it progresses , thus dim inishing the volu me that remain s to be 1 taken up through the p ipe . found that if I let the auger go ahead of the pipes and pushed the latter dow n periodical ly there w as always an accu mulatio n Of clay like that already cut to be cleaned out before the auger could be d ropped to the same w . I I depth that it had reached before This clay as not ashed , to o f w s an d so I obtained , the best my belief , a clean core ho e as diameter w determ ined by the internal diameter of the auger , and the danger of sampling the same ground t w ice over was escaped .

s O f I wo The particular ource error that uld call attention to , w s ho ever , is in concentrating and cleaning the mea ured sample before w eighing and calculatin g the value per cubic yard . T h e method adopted by myself to reduce this error as m u c h as pos s i w ble is - as follo s

The kapala I n ch ar ge of the bore I s a l lo wed to partly w a sh $ the w . o w s u sample , but n ever to ash it clean far he ho ld be permitted to go 1s a matter for in dividual j udgment .

Th e partially cleaned s a mp le is th e n d ri e d and put in a conveniently shaped bowl and a heavy liquid called bromoform w f is poured in . Bromoform hen pure has specific gravity o about and it fol low s therefore that quartz an d felspar w ill fl in b u t b e fO I e i w fl oat it , pou r ng Off the liquid ith the oating

w fi - . to n e quartz , etc it should be ell stirred prevent any grained tin ore being held up by s urface ten sion . After rinsing o u t the b m Of rm u r w w I o o a f r . bo l ith more un til all the q , etc , left adhering s w a s o u t o f e to the ides as the liqu id poured is got rid , ther w ill be a co nce ntrate at the bottom of the bow l of tin ore Ivith e n s o f w mixed h avy mi eral , some hich are su re to be mag netic

A s bromoform W l ll n ot mix w ith water this concentrate w is washed ith methylated spirit an d then dried . It is n ext brought u nder an ordinary magnet to remove magnetite if

and - present , then u nder a s mall electro magnet that removes al l i the com monly occurring magnetic imp ur ties such as ilmen ite ,

' ‘ ‘ u I . W e mon azite , to rmaline , and ron oxides or carbonate l h n this treatment is completed there will remain a Concentrate of

if Me ssrs . ffi n an d n f n w d d f o J. G S o s o $ a o n on v rt e bro m o r J. i i s L a e i s m r , g y , , 8 d d at 7 . 9 . er o un p p .

I o btain ed a v et h an d li ttle el ectI o m a n et f ro m Fuess te litz Berl in y y g , S g , , , at a co st (if abou t £ 6 Th e curren t is su li d b $ lle sen dr c ell s si x f . pp e y e r y , o wh ich i ve a ver owerf u l m a n e tic fi el d g y p g . 2 2

a I I e I h e d c ssiterite that may be pure , and can therefore be g a s w r w l tin ore ithout fu ther precautions , but that ill probab y contain — s om - i e n on magnetic impu r ties zircon , topaz , an d perhaps cor

u n d u m . S 15 upposing that zircon alone present , it may be fou nd possible I n rare cases to separate it by shaking the sample over

0 - w tin re s m c e i a 9 mesh sieve ithout loss of o , z rcon generally occurs i n v ery fi n e grain s and the tin ore m ay all be to o coarse

s - to pa s through a 90 mesh sieve . The same does n ot apply to w v I n t o f a topaz an d corun dum , ho e er an d the maj ori y c ses the best p I o c e d u re I s to w eigh the sample and then assay it for the A w e t i percentage of tin . assay w ill g ve the most accurate result , but a cyan ide pot assay , if not kept in the furnace too w ill long or too strongly heated , n ot introduce an appreciable error . It may be that metallic sulphide s are present in the con e en

“

. w w trate These can be broke n do n by heating ith n itric acid , w and the sulphur separated can generally be ashed o ff . I f any di fficulty I s experienced I II d oin g this o wing to the abu ndance of th c sulphu r , concentrate shou ld be boiled in aqua regia or ignited . N o attempt should be made to separate the zircon , topaz , or w w w corundu m from the cassiterite by ashing ith ater , as that is

’

e - T c rtain t o result in a loss of tin o re . he value of the assay is th is . It w ill i n nearly every case be possible to j udge to w hat assay val ue it w ill be possible to concentrate the o re i n” o f o f o r bulk , either by trial a smal l portion the grou nd by

‘ ‘ I I atc hin g similar o re being concentrated . S ay that it is expected that an assay val ue o f 74 per cent . can be reached an d that ' w h S 68 e r nt i a l eig ed amples assay p ce , it s easy to c lcu ate what would be the value per cubic yard at the higher assay val u e . Possibly the pu rchase and u s e of bromoform and an electro magnet may be held to be fatal obj ections to this method . The n I w ould suggest the follow ing procedure to guard against a large w r t e error . H aving taken over the partly ashed samples f om h S I e v e s kapala , dry them and separate them by mean s of into as r w many g ades as may appear n ecessary , and the n ash each grade separately . This w ill facilitate the cleansing Of the sample w ithout serious lo s s o f tin o re . It w ill very probably be obj ected that the bromoform magnetic m ethod errs in that it aims at extractin g the uttermo s t particle o f o re w s w s w wh at h e from the sample , herea the m iner ant to kn o n n rn 15 will be abl e to save i n practice . Here a fu dame tal p i ciple cal l ed 111 question on w hich it is i mpos s ible to speak too pl ai n ly . The object of sampling is to fin d out as nearly as possible the actual ti n - ore contents i n the grou nd o n the assumption that the miner w ill endeav o ur to work u p his perce ntage extraction as near N O w n : 1 . 0 0 per cent . as possible one ould expect an extractio of o fe w 1 0 0 per cent . t be reached , but people expect a miner to

“ advertise the fac t that his s ampl ing shows an apparen t extrac tiou f of mo re than 1 0 0 p er c ent .

’ natu re of the b e d natu re and size o f t

Charge . $ seful ad the ore determine heavy impurities . it is obvious that n