Many fine-grained igneous rocks, basaltic and felsitic in character, are difficult to classify. In numer­ous cases, it is impossible to classify these types of rocks by quick methods of identification. It was hoped at the beginning of this study that refractive indices of glasses formed by quick artificial fusion of samples from selected suites of igneous rocks would show a close cor­relation in chemical composition

Geach, Robert D.

Digital Commons @ Montana Tech

Montana Tech LibraryDigital Commons @ Montana TechBachelors Theses and Reports, 1928 - 1970 Student Scholarship5-1952An Attempted Determination of the ApproximateChemical Composition of the Livingston Volcanicsby the Fused Bead TechniqueRobert D. GeachFollow this and additional works at: http://digitalcommons.mtech.edu/bach_thesesPart of the Ceramic Materials Commons, Environmental Engineering Commons, GeologyCommons, Geophysics and Seismology Commons, Metallurgy Commons, Other EngineeringCommons, and the Other Materials Science and Engineering CommonsThis Bachelors Thesis is brought to you for free and open access by the Student Scholarship at Digital Commons @ Montana Tech. It has been acceptedfor inclusion in Bachelors Theses and Reports, 1928 - 1970 by an authorized administrator of Digital Commons @ Montana Tech. For moreinformation, please contact ccote@mtech.edu.Recommended CitationGeach, Robert D., "An Attempted Determination of the Approximate Chemical Composition of the Livingston Volcanics by the FusedBead Technique" (1952). Bachelors Theses and Reports, 1928 - 1970. Paper 371.OF THbyobe t D. GeachThesisbrnitted to the De art ent of Geologyin artial 'ulfillment of theeauire! ents for the Degree ofBac elor of cience In G ological Engineering'. "T.. CHOOL OF f;1I JESButte, ontana. y 1952AT TTIDPTED D TE"I TI NOF THE PP OXI TE CHEll.IICAL CO [POSITIONTHE LIVI TG TO! VOLCA!' res BY TH" F'US 'D B~ADTECHJIQUEby• D. GeachThesisubmt t t ed to the epartment of Geologyin Partial Fulfillment of theequirements for the De ree ofBachelor of Science in Geological Engineeringi 1 7 ,BI -T 0 UCTrICO JTE 'TSo.................................................. ..... ..........................13.LT 0BTl TED • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • •• 8.C CL 81LIOGRs.1 Y ••F T EC....................TIrIS. • • • • • • • • • • • • • •• 9................... 14 .L TELATE 2.Table1.ILLUSTR TION• • •• • •• • ••• • • • • • • • • • •• • •• • ••• • • • •• • •• • • • • • •• • •• •• • • • • • • • • • • • • •1.• • • •••••• ••••• • ••• • •• • • • •• • •• • • • • ••TABLE• • • •••••••••••• • • •• • • • • • ••• • ••10.11.9.T FTE T ~ \~I~' T I c<ro TIF H ~ LIVII G~T -LLC Ie BY THE USED BE DC 1.1 AUEby• • GeachITO CTI....r ny .lir:e- r ined i neous roc s , basaltic and .e1-itic in cb r cter, re i ic It to cIa sify. In numer-ou c eoit i i os ible to cl ~ ify these ty. es ofic met 0 of identific tion. It ~as hopedt the b inni g of thi t dy th~t refr ctive indices ofgl se .ormed by q·c arti icial fusion of samp es fromn 0 ~ roc S lould ~hog a close cor-e1 tic i che ic 1 it on. ince tbe deter lina-ti of .the ndex 0 refr ct·on with petrographic1c 0 co e, ne r 0 ed by the ' e 0 certain lie "ids oro e in i e rea e anIrelatively sim Ieew i_ tes, theoil 0 OJ i e 0 refr c io , isv e e y ue a i ~e -com osition correla-t 0 I t lS et hod coulrl be used,0 t 0 t 10 i eOl r· c s I sin iJ ar chemf,c 10 , but itt z ble t t t res and tin-e 1 1 e , 0 e "'d· ()or e it 011t the need0 t i e he ic ly e • ch0 0 ·~o ::ci ·t t o nl.t~on 0 the orecidic r ocks , he ore basic rocks, and the Lnt e rmed i.a t etypes.s a test of the idea, -ite of nineteen rocks,inly n e itic in co 0 ition, collected by ProfessorJobertson frot the Hat Cree ...section 0 the Livingstonvolc~nic ne r Elliston, ont na, ere sed by the riterin this t y. '0 r of the e roc~s, rangin from thecst cidic to the most b sic, ere selected .or che 1c 11y es. u pIes fro~ these analyzed rock ere thenpo~ ered, bjected to co~ 1 te fusion in a carbon rrc,a d their refr ctive i ices obt.i ed fror the reslltinglass beads by 011 i ersion ethod. Fro these refrac-tive incices, a co r~lation with the ~il c content ofthe analyzed roc~s s ttem~ted, an a curve sho~ingin ex v ri tio ~as re red. If sa .Ies from the re-m Lning fift een r ocks ve r e used, and thei refr ct iveice obt Lrec.....i i1 rly Lt '~a os tuLa t ed that t heilic contont 0 the e other oc S co Id be obtained byco s-correl tio on curve ~it10Ut the need for chemi-c 1 ith th silic content eter _ine] by thiset od, classificctlon of these rocks y simple petro-6r hie ecn ight be f ci it ted.HOlever., I t hews (2, .100) st tes that the techniquei at· thout it I-rit tic s For ex mple, the co rser-c i er oc nd .e rh» _ or iyr Le s , re not amena bleo t i roc ~ure. ~i ce the adv nt ge 01 the techrique-2-lies ·n the rapidit ith ~hich deter in tion c n benone (10 to 15 rni ut es ) , t he t Lme nd effort in gr Ind ngcoarser- zra I ed r-ocks ou Ld minimize t hd s advantage, andthe 0 ibility of v ri tion in sam les enters into ttep oeeclure. But s t ILl. mor e Lmjortant, a plication of the~ e t\ort ta e in stu~y of coarser- rained plutonitesor iner 10 ic 1 co 0 itio, ri.ch i a fairly reliableide 0 chen ic 1 co position, can be exercised. it easeno s: r ce , a d t is roceclure is si Ipler no or, s t-i f ctory. But for the fine-)r ine ock, the f sion-bea tecbni ue N s ho ed to be i~hout a substitue as anaajunct to petrogranhic cl~ sific tion.10KTh t t e in ex 0 refr tion of n tur 1 1 ss isndoub ely related to its chenic 1 composition, expressediter 0 in~le var 1e (silica content), has longbeen k 0 n ~ich eL St rk (1904) n '. • George (1924)tte ted cor elatio of refractive i ices of natur 1las ith t eir 111c conte t, but ~ithout any sur-e ce 0 cc rae. Their ab ervations sho~ that two glas-es (_ t ~it the e Lnd e 1'1 I gh t differ in silicaco tent by S L ch s 14 _er ee t, or that two, 1 ~ esit tee s il t c onte t _i ht differ by as much aso 065 i index. rther ore, t e earl or of Stark and'eor e aes ke it cle r th t the proportion of 0 e con-3-stituent alone oes not determine the refractive index 0a bIas; ho·ever, each constituent should, nd Derh psoes, contribute according to its mount and roperties.inee fe completely glassy rocks, directly s it blefo index determinations, are commonly found in the field,esch (1903) su gested thct p rtly crystalline rocks (apb-ntic roc~ ) could be rtlficially ~used to produce glas-ses itable for in ex-com osition tudies. Vital to thearti ici 1 fusion is the fact that important changes mayb b ought a out the com os~tion of the rock by elim-ination of wate , bringing iron to a niform state ofo idation, nd even erh p b the loss of some constit-uent by volctilizationollowing this line of reasoning, C •• ~athews (1951)arti ici lly fused sixteen selected rocks from the samem gm tic ouree in a Cc bon arc 1 mp; selected rock ,bec se the p lie tion o_ R r er's v riation diag ems(2, • 118-125) to ro 0 i neo s roc s , ofone en r 1 Icc lit nd e, does 0 that ithin suchro s t o rocks it simil r ilica cont_nt h ve si il rb 1 com osition d, if 1 ssy, ca be expected to have11 r re ractive ndices. The maximum dep rture in rat-e s' stu y 1 S 0 007 in index nd 1.8 per cent in silicacontent. Ithou h these re Its are far from erfect,t eir ccur cy see.e to j t·fy the riter m ki g a ikeinve t t on of hi 0-4-CElD EThe 1 boratory rocedure, folIo ed by the writer inhis st dy , .as develo ed by C. 11. J~:athews, and is outlinedin the ineralo ist, Vo.Iume 36, (1951). For theericabe efit of the re der, this rocedure is cited as follows:tI •• a rocl chi of ufficient ~ize to be represent-ati e ithin the Ii its of accuracy ~esired, i.e. yield-in an e ror of less than 1 per cent in composition, isbroken ro the h n s eci en If the rock is homogen-eo and fi e r ined or lassy a very small chi , weigh-i g erh s co Le 0 :lr ms , Ls ad equa t e; j_f, howev e r ,the roc{ i co rse grained or nor hyritic of, the chipt be con i er bl 1 r er, preferably of a size suchthat t e subtr ction of a sin Ie grain 0henocryst Jould not aterially effect the composition.The chi is then p Iveriz_d in mortar until a finenessnd degree 0 mixing is 0 tined s ch that any 10 mg.s m Ie 10 1 differ ro the e n comnosition of the mixles th n 1 er ee t. t such stage, ag in dependinn the o o~eneit a g ai ize of the original roc ,mos t i ot 11 the o der ould be -200 mesh. It is de-~i ble to lit the Ie, u in a a_ prove samplingtee ni e, at ever 1 st es in the gringing in order toi iz the ti e d ef ort involved "d iamond" ort rrov better for Dul erizing h rd vole nic rocks thanc t i 0 IDO t in iCl uf cie t iron ilings can be-5-ro"ucee ther Lng the ri i1e effecti ely.of a sin Ie chip to contamin-n a at e mor t r , t hough u --i ed or coarse r· din is Tell. ads ted for the latert :_)esof ~rin(i eriits nore thorough Li ing th noes the i ond mort r t irst, til this art of theten e has be~n nerfectec, it is adv· abl. to re eateter i tions using -i fer nt c1i off the s.me handeci en to e tRbli the ce r cy 0 S . lin" no ered s Ie i intro uced into broad cr ter....t :~.th the oint of enkpife to denth 0 abo t 2 mm ,i t 1.. I er end of the lo~er electrode of the c rbon arcneared cr r ens , 7 . m. in d m ter, nd us eo tertn ir e h VG ee t ered to bo t or e h If the originalter b e ns 0 encil sh r ener to re:1uce ot thei of the rc d the eat loss rom the vicinity0 the cr t it 1 this odi c tion the owd e r ed r-ockc 0 1 elt ., he rc ·th n ver ..1 secon J ,e 1 7 n t ~r r )t · g "0 t . ., enon I-te 1 o _ Cc e o .tained 0 ly ~ri t h0 0 e rc_ . It ..... t to t c) throu h darkil e the n tho 0 meltin to reeo nizeth ti t on h ed com letio terch th'-l rc e itc ~d off. If f si n is inCO·'1-the Ie s 1 i Ie ons it ent e ia L undis olve ,t 1 .... ~ill ot have t o no ·tio 0 the nhyc 0oct.• If ion is nece s rily 1. 010 ged ci t'e r e ial-boil n m y Ie to loss of vol, tale C Oli..S t i tu en t c! other......0th n t ". nd gain the co 0 ition of the glass rvill not--be t1 t 0 t e anhy rODS r ock , fter . rolonged heating,mo eo er, the elt Is 0 served into tne el ctrode on001 the gl ,...... i b ly clouded ith 0 .' a Ie gI. in ofc r on , T11e co _.os t t i on of the g l.a s s itself is un ffectedb t the i r tie k t e ef ctive index eter.i ationi ic It.It ~ ~~e 01 e ( h O_'ID n the cr-ter of thee e t 0 e ter t 18 c rc l1 s be~ swf.t che of'f is thenc she on t 1 1 t ~ n t e .n., ex 0 t e olass Ira1 -ent .eter nt.ned the 0 (1 iY) r immer on met hod in oils0.....1 0 n e r ctive i dex. I ch maxi tlm error ofbo O.04·n e rmf i Le in 0 tine'deterninations of't e in·ex 0 the las~, ns till greater acclracy ise i the nre on 0 t nerd curves from analyze~Ie, onoc ometic Ii at" virtu lly essent"al ithers od I v 0 or a ropri tely :iltere ~hite 11 hted bite 11 ht is n ti 8ctorye u d •01' tc cen svi t ~ee t o ti eost cc e010 rt ·t ro ce ... ~l_ce 0t _ e wh e 0 hav ne rl~ thech s t .n J..,"'8S of 0 lLst ebeen ureIt "-7-The roce re, ~t tee before, s closely 0110 edthe vr It e r ITineteen r-enr-e s e tative oc. sa :ple ereIve~ize in ~n orr i r llite mort r, d t .. owd e r-ederi 1 1 ce i ropri tely lab led vi Is. usionof e s mple a ade it 1 spectr~ ra hie c rbon rc,tb r ractive i dices e e obtained by the se or aet_oora n It ro co e an ·ndex of refraction liqui Oils.110 ever te { of 0 och o 4 tic lie t so:trce for usei co ct·o t e etro phic nic 0. cope, the riter_e filtere 1 hite li~ot, 1 hi h was t e only t pe ava·l-IeSlJLT BT 11 DThe in e 0 re r etion d t obt ned d ring the cour-seof t e tu i ot re It i t n rd or sy etric 1c rve, in ich t e vr i t e r had co .Li ence. hen the 1~ir tIe ere ed d t ,ir n "ic ,... dct r.ine the riter:l ,c t t if ere t 1 ,... rt·cle fro 1 the sr me be delde ic 0 re r ctio e tly i ere t I)i1\fer-. e x c s 0.06 e e recor ed , . h i ch fort e e s v r tion 0 16 per cent or n.or et n th t e i ,d. ucce'" iv ru s in T8 i 10 s ve r et on te t · e a time t d , beacu et of' e pos r to e ,e re 0 30000 . (t et t e 0 c bo rc) _0 ·t)le the eli -i t th oc ch s te n the1 0 01 ti iz ti n ever 1e ro o e ( cin en o. ?9-t -11) ith8the cArbon rc t times r nJlng from 1 to 20 seconds. Yet,vith this time factor, the variation in refractive indexproved too great for satisfactory composition correlation( ee 1 te 1). Ho ever, In er 1 ay, the final resultof the tUG did indic te th t ~cidic rocks, or those highin ilic conte t, 1elded 10 er refractive indices thanthe b ic rocl s. These results re surmn rized in Table 1,d sho n in the acce anyinb refr ctive index-com ositiondi ~r m (}l te 2).§. efractive Index28-155-1 D cite vitronhyre 69 2~'; 1.495 !. 0.0124-57-2-1 Trachyte 69. 4~~ 1.500 :: 0.0059-9-4 esite 58.7jb 1.545 = 0.0320-7 4-2 de ite 50.4~~ 1.570 :to.OlCO CL 8I F rrn E TIOI Since t ie ta reeo ed during the course of the studydie th t t e refr ctive index of a bead differe(l fort e e time, d 1 0 de ite the length of ti e of0 , ·t ge te y rofes or obert son tbat a1 1 evelo e over t e r ce 0 the bead dur-Ingort r ti e f f 0... the C Ibon rc. Consen.uently,r v t" bse uent thoro !h mix-t 1 orm t· on 0 1-9-- --- I/v~~11~9I \1.57' I \~ ! \ / ~, V '\1.55 /)V \1.t.53.... j1.51149zooo 2 4 6TI E. HO I G VA IA Q . QPL8 10 SEC.REFRAC IVE DICESQIF FU' 0 QC R GARDLESS OF TIMEPLATE 2%70 ~~~ '-<,<;60 =.r-,<,-.50401.50 '.52 1.54 1.56 1.58INDE OF REFRACTIONMELTRAM SHOWING R LATIONSHIP OF REFRACTIVEINDICES OF FUSED ACIDIC AND BASIC ROCKS1ing of the constituents in the elt, and, as a result,variation in refractive index o-ld be expected in thes mule s a wh o'Le , wh Lc h In na Ly: is 1NBS the materi 1e i ed for index of refr ction. nother factor whichmi ht h ve entered into t e fu ion is th t the carbon ofthe electrodes ight have reacted ~ith some of the rockco stituent , rticul rly ilic8, and have formed sili-con carbide, thus resulting in a new co l_ound, instead of -remaini g neutral as ssumed. third f ctor, suggestedby r. erry, is th t vol tile constituents may have beendriven 0 f , thereby, ch nging t 1e 'com osition of the ori-gin 1 rick; for ex m Ie, ater of crystallization may havebeen elimi ted, nd even sone of the met 11ic constit-uents, such as sodiu , c lcium, nd _otassiu may have been01 til lzed nd lost.In in 1 conel sion, the result of this study didnot yield the r esu.Lts ho e for, re u l t s wh i ch oul.d beof aid in i ve tig tion of fine-gr ine rocks. The studydoe, bo ever, hOI to fut re ~orkers that this procedurein research has m ny Ii it ti n hich detract from itsse Ld v e i race identi ication.eve a1 fut re reeo endations re offered by therite for t e bene it of tho e people whose interest mightlie conductin fut re research Ion these lines:1. The spec fic gr vi y of on-vesicul r sa pIesobt i ed b the use 0 pycro eter and cou led T ith-12-refractive i dices might ensure higher degree of accuracy,th n, as found out in this study, refractive indices alone.2. Fusion oints of p per-match-stick-~1zed rockles, mo_nted in non- usible base, somewhat in theanner of seLger con s used in a cer mics laboratory,might be taken for "eter lination of the rat 0 of fusingto refractory material resent in the rock, and thus proveto be an aid for r pid determination of the amount of someo the jor con tituents i~ the rock. Althouo this ro-cedure : e red to offer 0 sibilities of favorable results,the time av ilable did r-ot per1it the writer to follow~throu h the r ther ti e con umi ex erimental work needed.-13-BIBLIOG flY1. Geo ge,2. Harker, A., The atural History of Igneous iocks: ~ac-milJi noel York, 1909.3 the s,4. er ry , E S., Or·l Cumrn.nication, ontana Scboolof lines.5. obertson, F., Oral Cummnication, :ontana chcof of Hines.14-

An Attempted Determination of the Approximate Chemical Composition of the Livingston Volcanics by the Fused Bead Technique

http://digitalcommons.mtech.edu/cgi/viewcontent.cgi?article=1371&context=bach_theses

An Attempted Determination of the Approximate Chemical Composition of the Livingston Volcanics by the Fused Bead Technique

Abstract

Similar works

Full text

Available Versions

Digital Commons @ Montana Tech