Document RaKNjpnLmGej8ypOe70epbZ78

FILE NAME: RT Vanderbilt (RTV) DATE: 1976 Oct DOC#: RTV207 DOCUMENT DESCRIPTION: Dept of Health Report - Electron Microscopic Analyses or RT Vanderbilt Talcs Collected from Talc Suppliers FINAL REPORT l g x o /v - 2 _ 0 0 !G>0 5 r INDUSTRIAL, HYGIENE STUDY OF THE GOUVERNEUR TALC COMPANY, NUMBER ONE MINE AND MILL Balmat, New York Volume I I Talc Bulk Sample Analyses By NIOSH, WC McCrone and Mi S in ai School o f Medicine Department o f Health , Education, and Welfare Center for Disease Control N ational I n s t i t u t e o r Occupational S a f e t y and Health :ion o f S u r v e i l l a n c e , Hazard Ev a lu a tio n s and F i e ld S tu di es C i n c i n n a t i , Ohio C orrsm - 3 I- 1 A Electron Microscopic Analyses of RT Vanderbilt Talcs C o l l e c t e d from Talc Suppliers Analyses Performed By John M- Dement Ralph D Zumwalde Date October , 2976 Department o f Health, Ed ucation, and 'Welfare Center for Disease Control National I n s t i t u t e for Occupational Safety and Health D iv is io n o f S u r v e i l l a n c e , Hazard Eval ua tio ns and F i e l d S t u d i e s C i n c in n a t i, Ohio ix INTRODUCTION As a p a r t o f ongoing research by the N ational I n s t i t u t e for 0 occupational. S a f e t y and Health (NI05H) concerning h e a l t h e f f e c t s o f occu p a tio n al exposures to t a l c and as requested by the Occupational S a f et y and Health Administration/ seven bulk t a l c s produced by the R T Vanderbilt were analyzed f o r a s b e st o s content. These t a l c s were obtained from independent t a l c s u p p l i e r s and have been " c e r t i f i e d " by Vanderbilt not to conta in a s b e s t o s . Samples were an aly se! f or a s b e s t o s c o n t e n t Jby a n a l y t i c a l e l e c t r o n microscopy fhe f o l i o nq para graphs d e s c r i b e sample preparation and a n a l y t i c a l methods employed along with results. METHODS Given in Table 1 are d e s c r i p t i v e data fo r the 7 t a l c s obtained and analyzed in c l u d i n g source and NIOSH sample number assigned., y Samples for transmission e l e c t r o n m icr osc opic a n aly s es were prepared by d i s p e r s i n g the powder samples in e t h y l a c e t a t e by u l t r a s o n e r a t i o n Approximately 10 rrg o f each powder was plac ed in 10-20 ml. of e t h y l a c e t a t e followed by v ig o r o u s u l t r a s o n e r a t i o n f o r 10-15 minutes using a c e l l d is ru p t er . Samples were prepared using a micro c a p i l l a r y tube to p la c e a drop o f the s o lu t io n onto 200 mesh Formvar/carbon s u b s t r a t e copper e l e c t r o n microscope grids e t h y l a c e t a t e was allowed t o evaporate in a laboratory c l e a n hood. neces s ary , an a d d i t i o n a l drop o f the s o l u t i o n was used to in su re s u f f i c i e n t m a t e r i a l f o r e f f i c i e n t a n a l y s i s by e l e c t r o n microscopy Blank g r i d s were prepared in the same manner as the samples,, Samples were analyzed by f i r s t scanning the e n t i r e gri d a t low m a g n i f i c a t i o n to ascertain the s u it a b ili t y of the preparation fcr an alysis ai a magnifica t i o n o f approximately 17,000X, a l l p a r t i c l e s with an a s p e c t r a t i o { le n gt h to diameter) o f 3 to 1 or g r e a t e r were i d e n t i f i e d using both s e l e c t e d area e l e c t r o n d i f f r a c t i o n and energy d i s p e r s i v e microchemical a n a l y s i s f o r f i b e r i d e n t i f i c a t i o n , A t o t a l o f 25 to 50 i n d iv i d u a l f i b e r s were so analyzed f o r each sample, a JEOL, JEM 100B t r a n s m i s s i o n / s c a n n i n g e l e c t r o n microscope equipped with an EDAX energy d i s p e r s i v e x-ray a n aly ze r was used for a l l a n a l y s e s . Electron micrographs of typical fibers along with their d iffr a c tio n p a t t rns and x-ray spectrum were recorded f o r each sample 2 Table i Sources o f R.T. V and er bil t Talcs Produced at the Gouverneur Talc Company, Number One Mine and Mil! and Obtained from Su pp li ers Nytal 300 Nytal 400 5x 325 X FT 3x Crone Chemical P.0 Box X4042 Houston, Texas 77021 Paul C ra zi e r Company 1115 S ilv e r St. Houston, Texas 77067 001 - 002 003 004 005 006 007 3 RESULTS AND DISCUSSION R es u l t s o f a l l a n a l y s e s are shown in Table 2 and t y p i c a l micrographs o f f i b e r s in these samples along with e l e c t r o n d i f f r a c t i o n p a ttern s and x-ray s p ect ra are shown in the Appendix, Based on t h e i r s e l e c t e d area e l e c t r o n d i f f r a c t i o n p a t t e r n s , f i b e r s were c l a s s i f i e d as p o s i t i v e amphiboles, p o s i t i v e c h r y s o t i l e , n o n - a s b e s t o s or "ambiguous" meaning t h a t the p at t er n was not s u f f i c i e n t l y c l e a r for p o s i t i v e i d e n t i f i c a t i o n . The eneigy d i s p ersiv e x-ray spectra were used to c l a s s i f y the amphiboles as to type and for f u rt h er c o n fir m at io n o f c h r y s o t i l e i d e n t i f i c a t i o n by e l e c t r o n diffracti on, As shown in Table 2, r e s u l t s o f t h e s e an a ly se s show a l l t a l c s analyzed to be o f e s s e n t i a l l y the same f i b e r composition. The major f i b e r component i s a s b es t if or m a n t h o p h y l l i t e , ranging from 67 to 88% o f tire f i b e r s p r e s e n t in addition to f ib ro us t r e m o l i t e (4 to 12%), Aspect r a t i o s fo r thes e f i b e r s ranged up t c 1000 to l , w i t h the l o n g e r , thinner f i b e r s bein g a n t h o p h y l l i t e . Trace q u a n t i t i e s o f c h r y s o t i l e were found in two o f the s a m p l e s . C h r y so t i le f i b e r s observed were s m a ll in diameter (< 0,1 urn; and s ho rt in l e n g t h (most < 1.0 m ) - Table 2 Summary o f NIOSH Electron Microscopic Analyses of Talc Produced at the Gouverneur Talc Company Number One Mine and Mill Samples Obtained Frcm Talc S u p p l ie r s Talc Sample .. Nytal 400 Range of Fiber, Aspect Ratios .......... 3/1 to 1000/1 Fiber Iden tification (Percent) Pd_s. tlve: Amphiboles Tremoli te Anthophyllite Positive Chrysotile 8 38 N.D ~ Nytal 300 3/1 to 100/1 12 72 N.D. 5x 5/1 to 100/1 11 80 Trace X 8/1 to 80/1 6 80 N.D. 3x 5/1 to 100/1 12 67 N D FT 3/1 to 50/1 16 72 N.D. 325 3 / 1 to 50/1. 4 88 Trace t...... - .... ----------------- * Selected area d if f r a c t i o n patterns not s u f f i c i e n t for p ositive i d e n t i f i c a t i o n ND - None Detected CONCLUSIONS Using present "state-of-th e crt" techniques for asbestos finer analyses a ll 7 ta lcs analyzed demonstrated large quantities of asbestiform tremolite and a n t h o p h y l l i t e t o pr es en t. Only t ra ce q u a n t i t i e s o f c h r y s o t i l e wera d etected i n 2 o f the 7 talcs., Based on these analyses, a l l t a l c s analyzed should be la b el ed with the OSH& a s b e s t o s warning lab el . i ! i; 5 " ;--*>r-::v- ;.r *y>7 ; y ro. ^ ? ,. r. : ,,7 ''' '" '. ;- ' ^ - O oj. ' :-O O . -: ;: v '. *y;7viv' ' :;! ;;; J f :. : . : : . O' : , Jf- 0 ? :J' '-v 0>Vv. ;i ' -,v:.;:*^;i. y v >: t*1.y '<:O.;r[ it : '. < ' .-.r. M ';. r. i , :i APPENDIX t Electron Micrographs, Electron D i f f r a c t i o n Patter ns and X-Kay Specta for Typical Fibers in RT, Va nderb ilt T a lc s n 7  t} MOUNT SINAI S CHOOL OF MEDICINE , of The City University ojNew York F I F T H A V E N U E A N D I 0 0 T H S T R E E T * N E W YOR K. N Y , 10030,. Dr/uirimfnl of CommunityCMtdicint Apr i l 29 '1976 Mr . .John Dement NIOSH Room 527 Post O ffice Building F i f t h and Wslnut S t r e e t C in c in n a t i , Ohio 45202 Dear Mr. Dement : Th is report covers the r e s u l t s of a n a l y s e s of seven NYT.3L samples; .400, 3 5 , X, E'T, 300 325 and 5X. The seven samples were analyzed q u a n t i t a t i v e 1p f o r t hr ee v a r i e t i e s o f a s b e s t o s m in era ls " c h r y s o t i l e , a n t h o p h y l l i t e and t r e m o l i t e and a l s o f o r quartz Ana ly t ic a l techniques included polarized optical microscopy, x-ray diffraction, t r a n s m is s i o n e l e c t r o n microscopy and scanning e l e c t r o n microscopy with energy d isp ersiv e a n a ly t ic a l systems. Q u a n t i t a t i v e determ inations by x~ray d i f f r a c t i o n of the four minerals in quest i o n were made by comparison with d i l u t i o n standards of t h e s e minerals, A uniform method o f back mounting in which t h e sample i s remounted and re-run four times at id e n t ic a l instrumental s e t t i n g s over d ia g n o stic r e f l e c t i o n s has been shown to be re p ro d u ci b l e and accurate., Q u a n t i t a t i o n of t h e s e m ineral s was a ls o done by x - r a y d i f f r a c t i o n in the s t e p - s c a n , f i x e d count mode I n te g ra t ed i n t e n s i t i e s for d i a g n o s t i c x - r a y r e f l e c t i o n s were measured using both t h e back-mounting and s t e p - s c a n t ec h n iq u es When refer red t o c a l i b r a t i o n curves prepared by each technique, t h e NYTAL unknowns showed egreement, averaging about 10% standard error. The r e s n l t s are as f o ll o w s : l 1 \ CO r"1. NTTAL 400 U 3x IT X M FT If 300 n 325 5x SERPENTINE PHASE CtTo 14-18 31-35 26-30 26-30 14-18 19-23 14-18 TREMOLITE % 24 32 50-60 17 18 24 27 ANTHOPHYLLITE 2-3 not detected not determined not detected 4-5 5- 7 7--9 QUA KTZ etyo 7-10 9-10 * ' not detected 9 . - 1 !\ 3-4 7 8-9 i Because of the larg e amounts o f t r e m o l i t e (50-60%) present in sample X `Efithophyl- ^ l i t e could not be q u a n t i t a t i v e l y determined by x - r a y d i f f r a c t i o n Howevr . y s i s of f i b e r s on the SEM shdws that a n t h o p h y l l i t e i s present. X-ray ndicated the presence of s e r p e n t in e phases in a l l samples, but the ral s p e c i e s of t h i s group which' in c l u d e s c h r y a o t i l e , a n t i g o r i t e and, aid not be p o s i t i v e l y i d e n t i f i e d although the l a t t e r m o s t c l o s e l y *ray p at ter ns . Examination by TEM and SEM with energy d i s p e r s i v e em confirmed t h s t v i r t u a l l y a I 1 o f the sperpentine phase c o n s i s t s / ' C h r y s o t i l e was d e t e c t e d by e l e c t r o n microscopy in the samples. , :ying phoxomicrographs) . er-, prepared f or a n a l y s i s by t ra n s m is si o n e l e c t r o n microscopy by chnique which did not a l t e r the s i z e d i s t r i b u t i i n o f p a r t i c l e s Two t hre e EM g r i d s were scanned at. 25,000:c m ag nification on a Hitachi ;cope. Fibrous p a r t i c l e s were abundant in a l l seven samples. , Morphol y s t a l cleavage c harcct e ri s ti 13 indicated the presence'of amphibvles. fied by observing a t y p i c a l la yer-type se le c te d area .electron d i f f r a c on the fi b r o u s p a r t i c l e s . The la y e r li^ne distan'ce normal t o the :is was c o n s i s t e n t l y observed to be 5.3A, which i s c h a r a c t e r i s t i c o f - :peat of amphiboles. These p a r t i c l e s were defined as amphibole and >n on a grid f a c s i m i l e recorded. The specimens were t ra n s f er re d t o ectron microscope (CWIK-SCAN) equipped with an energy d i s p e r s i v e x - r a y The amphibole ,,particles were analyzed by point count and were found two gen era l m or p h o lo g ic al -ch em ic al ty pe s of populations which permits rfined as d i f f e r e n t mineral s p e c i e s , T h e 'long, th in f i b e r s ( as pe ct more) showed Sl/Mg in r a t i o s c o n s i s t e n t wi t h a n t h o p h y l l i t e coraposi- f i b e r s contained l i t t l e or no iron. Short prismatic f i b e r s with , from about 3/1 t o Si/Ca/Mg proportions c o n siste n t e. No iron was found i n i t r i c 1i t e . ___ Arthur S. Kohl , Ph.D. Environmental Sciences Laboraxory t-* ' I C h r y s o t i l e - t a l c standard d i l u t i o n - step-scanned 0 , 0 2 de gre es two t h e t a over 5 66 A (004) r e f l e c t i o n ( 2x 10** ) F i g u r o l; C u l l i m i l i o n o f A a b u ^ t lf o r m AtnphUio 1ua unti'Omu'tv. i n T u i e II * Vv *,,iyws osteti ? f \ r -, -;*ti : t\ 4 } W l ' ^ yip'j y p jum or; <*Y- -K Oo <h k " >D r>i i Vi - 6 C* hfv i-'- S n \ w i \ aV Tt f\Jf\ ? `ULi N* 3'SX'f1i 3l1i0130* 0H tmJ ' J V1v' r 0 jv V\ I K M t U r t i * U t X EJ /fiTVif h,iv*e;i u'jniiiKi ni -nt`t: mn Report to Dr. John Dement NIOSH Cincinnati, Ohio 45202 ',&*i : *;... .y-- ... A- t EXAMINATION OF TALCS FROM GOUVERNEUR DISTRICT -- NEW YORK Date- 12 D ecem ber 1975 MA Number: 4800 Copy \ of lr walter c.mccrone associatesene. 2820SOUTH MICHIGAN AVENUE CHICAGO, ILLINOIS 60676 13 an TABLE OF CONTENTS Summary Introduction M a te ria l and Method ofConducting T e s ts Light Microscopy X -ray Diffraction Electron Microscppy Results Light Microscopy X-ray* Diffraction Electron Microscopical Examination Conclusions \ ' : Page do . 1 1 2 2 2 2 3 3 3 4 ? 10 waiter c me crone associates, inc. 14 EXAMINATION OF SEVEN TALCS FROM THE GOUVERNEUR DISTRICT, NEW YORK SUMMARY An extensive examination has been c a rrie d out of seven talcs subm itted by the National Institute of Occupational Safety and Health, to determ ine their asbestos content. These talcs all originated from the Gouverneur D istrict of New York State and w ere identified by num ber code in the s e r ie s 83775-837G1. E xam ination was c a r rie d out by a com bination of light m ic ro s c o p y , using both polarized light and dispersion staining, x -ray diffraction, and electron microscopy combining electron diffraction and elemental analysis. The re su lts of the exam ination showed the p re sen c e of asb estifo rm amphibole in all seven sam ples. The amounts of the total amphibole and of the fibrous amphibole differed between the various sam ples. In all cases the prin cip al asbestiform amphibole was identified as trem o lite, but this was of a low calcium variety, containing approximately 2-3% calcium. In Sam ple 83757, x - r a y diffraction exam ination su g g ested that, a s m a ll percentage of anthophyllite was also present. Examination by light m icroscopy, however, could not conclusively differentiate between anthophyllite and trem o lite in this sample. The identification of trem olite ra th e r than a calcium bearing anthophyllite in all sam ples was based on the extinction angle, observed under c ro s s e d p o lars, of the fibrous amphibole. 15 waiter c.me crone associates, inc. INTRODUCTION The National Institute of Occupational Safety and Health is currently sponsoring a study of occupationally related disease in the talc industry . As part of this study, W a lte r C. M cC rone A s s o c ia te s , Xnc., has b e e n c o n tra c te d to study and ch aracterize the raw talc o res, The p re se n t work is re la te d to this m ajo r program and is concerned with a study of seven specific sam ples from the Gouverneur talc ore body. M aterial and Method of Conducting Tests Seven talc s a m p le s w e re s u b m itte d to W a lte r C, M c C ro n e A s s o c ia te s , by Jo h n D em ent of NIOSH. T1 e s e s a m p le s w e r e identified by n u m b e r s running in sequence from 83755-83761. No indication was given of the sam p le location w ithin the G o u v e rn eu r talc body., The s a m p l e s w e re ex am in ed by lig h t m ic ro s c o p y , using both polarized light and dispersion staining, x -ray diffraction, and transm ission electron m icroscopy combined with electron diffraction and elemental analysis. Light m icros copy Perm anent mounts w ere prepared for all seven sam ples, using A r o c lo r 5442 as a m o u n tin g m e d iu m . T h e s e p r e p a r a t io n s w e r e ex am in ed u n d e r partially uncrossed polars to obtain a general indication of the m ineral types p re s e n t together with their sh ap es and sizes. Sam ples fo r exam ination by dispersion staining were prepared using Cargille high dispersion refractive index liquids with n values of 1.550 and 1.605 . The low er re fra c tiv e index was used to examine the serpentine content of the talcs; the higher value was chosen to enable identification of the amphibole present. Exam ination by d isp ersio n staining was at a magnification of approxim ately 200X in plane polarized light. X-ray diffraction For x -ra y diffraction examination, sam ples of the powders w ere packed into aluminum cup holders and placed in the N orelco d iffra cto m e te r. The sam p les w ere ro ta te d around 3-n a x is p e r p e n d ic u la r to the a x is of the d if f r a c to m e te r which was scanned through a 29 range from approxim ately 6" to approxim ately ___ _---------------------------------------------------------------------------------- * waiter c, mecrone associates, inc. 60" with a scan n in g speed of 1 p e r m inute and a c h a r t sp ee d of 1 /2 inch p e r minute , Cu radiation, nickel filtered, was used at an accelerating voltage of 42 kV, and a c u r r e n t of 25 m illia m p s . The q u a rtz content of the s a m p le s was d e te rm in e d by s te p sca n n in g through the 3.35 A Line fo r q u a rtz and comTM paring the resulting data with that for "spiked" standards of quaetz in talc. T he s te p in c re m en t w as 0 01, 20 with a counting tim e p e r step of 50 s e c s . , an 8 sec, tim e constant and a chart speed of 1/8 inch per minute,, Electron microscopy For electron m icroscopic examination sam ples of the powder were suspended in isopropanol and lightly ultrasoneratecL A drop of this suspension was placed on carbon coated Nylon grids. Exam ination of the sam ples was / c a rrie d out in a combined e lec tro n -m ic ro sc o p e -m ic ro p ro b e -a n a ly ze r, EMMA-IV. The sam ples were examined and photographed at several different magnifications, electron diffraction patterns were obtained from typical fibers present and energy dispersive x -ray analysis was perform ed on these fibers, DJTvTj1C?UTT.LTli*fTtZC)* 1) Light .microscopy The following general, statem ents can be made: All the sam ples contained a serpentine which, on the basis of dispersion staining and morphology, has been identified as lizard itc. C hrysotile (the asbestiform variety of serpentine) and antigorite w ere not detected., All the sam ples contain trem o lite identified by d isp ersio n staining and polarized light m icroscopy and, although it would be possible to m iss a sm all p erc en ta g e of anthophyllite p a r tic le s ,s in c e m o st anthophyliites give n e a r ly the sam e dispersion staining colors as trem olite, appreciable amounts of anthophyllite would not be m is s e d b e c a u s e a s ig n ific a n t n u m b e r of p a r t i c l e s would Lie in the proper orientation for positive identification., With the exception of an occasional particle in Sample 83757, all the p articles which showed the tre m o lite / anthophyllite dispersion colors showed oblique extinction under crossed polars ( y Ac = 17-18"), thus identifying them ns tre m o lite , 17 waiter c me crone associates, inc AH sam ples contain talc in a form which looks like fibers. T hese g iv e typical talc colors by dispersion staining, T he m a jo rity of these talc fib e rs a r e a p p aren tly long talc rods.. T h ese ta lc fib e rs a r e esp ecially long in S am p le 8375c # M ost sam ples a re believed to contain a little quartz on the b a sis of the light m ic ro sc o p ic a l examination, It is difficult to put an acc u ra te value to the amount of quartz present, sin ce it is ex trem ely difficult to distinguish between quartz and lizardite under dispersion staining conditions., A calculation of the percentage of amphibole present and of the portion of this am phibole which was fib ro u s was m ad e as follows., F i r s t the portio n by volum e of the total tre m o lite p resen t as fib e rs was estim ated taking cognizance of both p a r tic le s iz e and n u m b e rs present., Subsequently, 30 fields in each s a m p le w e r e exam ined in detail ancT the p e rc e n ta g e by a r e a o f the total p a r tic le a r e a occupied by amphibole particles was estimated. Table 1 sum m arizes the observations m ade by light microscopy,, X -ray diffraction All sam ples showed the presence of talc, an amphibole and a serp en tin e . Inconclusive evidence of q u a rtz was detected by x - r a y d iffractio n on the norm al scan. By step scanning, however, low levels of q u a rtz w e re found. T he q u a rtz d ata a r e p re s e n te d in T ab le 2 and F ig u r e X. The serpentine m in erals are difficult to distinguish from each other 1 by x -ra y diffraction, A paper by Mumpton indicates certain lines which may be used to distinguish the three serpentine polymorphs provided that the sam ples a re relatively monominerallic. Specifically, Mumpton mentions that lizardite is c h a r a c te riz e d by a s tr o n g doublet a t 1,531 A. T h is doublet has indeed been observed on our x -ra y diffraction trace, thereby confirm ing the light m icroscopical id en tificatio n of Lizardite by d is p e rs io n stain in g . C h a r a c te riz a tio n of c h rv s o tile a s b e s to s and o th e r m e m b e r s o, the s e r p entine. group o f m in e r a ls , Siem ens review X.Li (X974) 7 th s p e c ia l is s u e , X - r a y and Electron Microscopy Sews. 18 waiter a me crone associates, inc. Sample Table I Summary of Light Microscopical Data ^ 83755 ^ 83756 83757 ^5 83758 X - T=* 83759 83760 -- 3>C.-- 83761 Total trem olite (% of sam p le by trea) 25-30 Fibrous tremolite (estimated % by vol. of total tremolite) 5 Quartz 4* Serpentine + Talc "fibers" (rolls,shards etc.J + Comments 15-20 20-25 25-30 25-30 15 -20 25-30 25 8-10 possible , + ? '- + 4- 5 1 25 10 + -? +V +? + ? 4- probable prcbabl + +(loog) 4* 4- large trem olite plates large particle size sm all particle size r rtx 19 tt i Table n Trem olite and Quantity Content of Talc Samples Sample 83755 83756 83757 83753 83759 83760 83761 Q uartz Content** Content tremolite 2% 1/2-1% -- 1 1/2% ~1 1/2% < 1 /2 % below 1/2-1% / r detection lim it 40-50% 50-60%*? 40-50%* *'60% >50-60 % * 5 0 -6 0 % 40-50% ** Step scanning data. * Indicates possible anthophyllite p resen t in addition to trem olite. 20 T his leaves only the amphibole to be ch aracterized in all seven The p r im a r y am phibole o b s e r v e d is trem o lite. T h s diffractio n ved a r c c o n sis te n t w ith ASTM C ard 13"437 fo r tre m o litc and w ith ata f o r tre m o lite s f r o m th e G o u v e m eu r district, In one s a m p le , ample 83757, a distinct sid e peak on the tre m o lite 8-410 line is id it is believed that this sid e peak is due to the p re se n c e of som e ;e. L e s s distinct evidence of this sid e peak is also p r e s e n t on 56 and possibly also 83759 (s e e F ig u r e s 2-8 for a c o m p a ris o n of 29 range on th e se sam ples)., As is c le a r fro m these fig u re s / in the side peak attributed to anthophyllite th ere is considerable t the ratio of talc to amphibole in these sam ples , An attem pt to his relationship in term s of percentage of amphibole present is also ble 2,, :on m ic ro s c o p ic a l e x a m in a tion.. Electron microscopical examination shoned that all seven sam ples s ta n tia l am ounts c fib ro u s m a t e r i a l . T h is w as h ig h e st in S a m p le .owest for Samples 83756 and 83761. Several typical electron m icro wing general areas of the sam p les a re appended to this re p o rt T 7). The electron m icroscopical examination concentrated or the terial and an attempt was m ade to estim ate how much of this m aterial asbestiform, that is, a fibrous amphibole as distinct from the fiber dc consisting of ribbons, sh ard s, rolls, etc. This examination was Doth by e le c tro n diffraction and by e le m e n ta l a n a ly s is u s in g e n e r g y x -ra y . The r e s u lts of th e s e e x am inations a r e s u m m a riz e d m Table 3, ited percentages being based on occluded area. Some typical electron hs, diffraction p a tte rn s and e n erg y d is p e r s iv e x - r a y s p e c t r a a r e In none of th e se fibers exam ined was th e re a p a rtic u la rly high p e rcalcium noted; however, calcium was observed at the level of the -3% in all the am phibole fib e rs ex am in ed . T he only co n clu sio n which Table IH Electron Microscopical E stim ates of F iber Content Sample 83755 Total fibers Fibrous amphibole (as % of total sample) -10% <5% 83756 "10% <5% 83757 83758 ~40% -30%. 83759 83760 -*5-10% -20% 83761 "***10% 15-20% 10-15% <5% 5% <5% ti i | f ft c i Table IV Overall Data Sum m ary sample 83755 83756 83757 83758 83759 83760 83761 Total fibers (TEM) 10% Amphibole fibers1 (TEM) <5% . Total amphibole2 (XRD) 40-50% Total amphibole^ (LM) 25-30% Fibrous am phibole' (LM) 1-2% Serpentine^'^ (XRD) 10-15% Quartz6 (S*S. X-RD) 2% 10% <5% / 50-60% 15-20% 3-5% 10-15% 1/2-1% 40% ' 30% 5-10? 20% 10% 1 5 -20% 10-15% <5% 5% <5% 40-50% "'60% >50% 50-60% 40-50% 20-25% 25-30*4;; 25-30% 15-30% 25-30% 1-3% 1-2% <1/2% 3-5% 2-3% 10-12% 10-12% -15% -20% -3 0 % - 1 1/2% -1 1 / 2 % <1/2% B.D.L. 1/2-1% NOTES: L Based on occluded area 2. Estimated weight percentage .3. Based on occluded a re a 4, Derived from estimated % of total amphibole which was fibrous. 5. Identified as Uzardite by light microscopy 6* SS. XRD = Step scanning x - r a y diffraction See also Table I 23 can be drawn from the electron diffraction and energy dispersive x - r a y analysis is that one has a fibrous amphibole of the tremolitu or anthophyllite type. It is generally not possinle to distinguish between tremolite and anthophyllite by elcctrc;;1 diffraction and one would therefore be tempted to suggest' that the fibers were anthophyllite with a trace amount of calcium. Taken in conjunction with the light microscopical examination, however, during which a diligent search was made, particularly on Sample 83757, for fibers which might be anthophyllite rather than tremolite, cne is forced to the conclusion that, rather than being a calcium bearing anthophyllite, the fibers are in fact a low calcium tremolite. The aspect ratios of many of the fibers obser ved are quite high and numerous fibers, such as those shown in Figures 20, 22, 24 and 30 showed the cl a ss ic fibrous structure of the asbestos minerals. There is no doubt in our minds that these are indeed asbestos fibers rather than cleavage fragments of a m o re m a s s i v e amphibole Mas sive forms of the amphibole are, however, present and the fibrous amphibole content represents only a fraction of the total amphibole content of the samples. CONCLUSIONS Table 4 summarizes the results of all the investigations which we have carried out. In answer to the specific question, "Do these particular talc samples contain any asbestos minerals?'*, the answer must be an unequivocal y e s . The asbestos mineral present appears to be a low calcium tremolite and is definitely asbestiform by any definition of the word.. The asbestos content in the samples v a r i e s from le ss th a n 5% to approximately 20%, based on occluded areas observed in the transmission electron microscope. Respectfully submitted, Ralph J. Hinch, Jr. Senior Research Scientist Aichard J. Slumps Research Chemist L Ian M . Stewart Manager, Electron Optics Group waiter cm ccrane associates,inc. FIGURES 1 THROUGH 4G , EXAMINATION OF TALCS FROM GOTJVERNEUR DISTRICT -- NEW YORK fFigure i Step scanning data for quartz Sample 83757 (003) Talc (a-SiCy-> 'AS* Sample 83758 (004) Talc (aSiO ^ ) Sample 83759 (005) Talc (a-SiO +) Sample 83760 (006) Talc (a-SiCy-) z.sr --------- --- ... ............ .. . Sample 83761 (007) Talc (a - S i 0 9-M 26 waiter c me crone associates, ine. ~ \oy 12 i t i i i i Figuro 2 ''vi 4 CB (0 O O o X-RAY DIFFRACTION DATA Sample Wo. i ........... Project No. * i Material ........ ................................ . ...... .M lffX t.............................................. =. Radiation rrFd-r*........ 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