Document 15Jo9XY2Dvwv0zNdZd4oVxJga

FILE NAME: RT Vanderbilt (RTV) DATE: 1975 Dec 12 DOC#: RTV127 DOCUMENT DESCRIPTION: Consultant Report to NIOSH - Examination of Talcs from Gouverneur District - NY . Report to De. John Dement * NIOSH Cincinnati, Ohio 45202 - .............. /Tj-v*. ^ V i ,, i fvV'... -' i'J .*. i . " - r V 4- EXAMINATION OP TALCS FROM GOUVERNEUR DISTRICT -- NEW YORK Date1 12 December 1975 MA Number: 4800 Copy y. of Jr waiter c.mecrone associates, inc. 2820 SOUTH MICHIGAN AVENUE CHICAGO, ILLINOIS 60676 * 13 T T T T T JM TABLE OF CONTENTS Summary Introduction Material and Method of Conducting Teats Light Microscopy X -ray Diffraction Electron Microscopy Results Light Microscopy X-ray Diffraction Electron Microscopical Examination Conclusions A /s .v-> V Page no. 1 * 2 2 2 2 3 3 3 4 7 10 1 waiter c mecrone associates, inc. 14 T T T EXAMINATION OF SEVEN TALCS FROM THE GOUVERNEUR DISTRICT, NEW YORK SUMMARY An extensive examination has been carried out of seven talcs submitted by the National Institute o f Occupational Safety and Health, to determine their asbestos content. These talcs all originated from the Gouverneur D istrict of New York State and were identified by number code in the se r ie s 83775-83761. Examination was carried out by a combination of light m icroscopy, using both polarized light and dispersion staining, x-ray diffraction, and electron microscopy combining electron diffraction and elemental analysis. The results of the examination showed the presence of asbestiforra amphibole in all seven samples. The amounts cf the total amphibole and of the fibrous amphibole differed between the various samples. In all cases the principal asbestiform amphibole was identified as tremolite, but this was of a low calcium variety, containing approximately 2-3% calcium. In Sample 83757, x-ray diffraction examination suggested that, a sm all percentage of anthophyllite was also present. Examination by light microscopy, however, could not conclusively differentiate between anthophyllite and trem olite in this sample. The identification of trem olite rather than a calcium bearing anthophyllite in all samples was based on the extinction angle, observed under crossed polars, of the fibrous amphibole. waiter c/nc crone associates, inc. T T T 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 thin study, Walter C. McCrone Associates, Xnc., has been contracted to study and characterize the raw talc ores, The present work is related to this major program and is concerned with a study of seven specific samples from the Gouvemeur talc ore body. Material and Method of Conducting Tests Seven talc samples were submitted to Walter C. McCrone A ssociates, by John Dement of NIOSH. T1 es'e samples w ere identified by numbers running in sequence from 83755-83761. No indication was given of the sample location within the Gouverneur talc body. The sam ples were examined by light microscopy, using both polarized light and dispersion staining, x-ray diffraction, and transmission electron microscopy combined with electron diffraction and elemental analysis. Light microscopy Permanent mounts were prepared for all seven sam ples, using Aroclor 5442 as amounting medium. These preparations were examined under partially uncrossed polars to obtain a general indication of the mineral types present together with their shapes and sizes. Samples for examination by dispersion staining were prepared using Cargille high dispersion refractive index liquids with n values of 1.550 and 1.605. The lower refractive index was used to examine the serpentine content of the talcs; the higher value was chosen to enable identification of the amphibole present. Examination by dispersion staining was at a magnification of approximately 200X in plane polarized light. X-ray diffraction For x - r a y diffraction examination, sam ples of the powders w e re packed into aluminum cup holders and placed in the Norelco diffractometer. The samples were rotated around 3-n axis perpendicular to the axis of the diffractometer which was scanned through a -28 range from approximately 6" to approximately - -- - ---------- 1 waiter c mecrone associates, inc. T T T T T t i 60" with a scanning speed of 1* per minute and a chart speed of 1/2 inch per i minute. Cu radiation, nickel filtered, was used at an accelerating voltage of 42 kV, and a current of 25 milliamps, The quartz content of the samples was determined by step scanning through the 3.35 A line for quartz and com paring the resulting data with that for "spiked" standards of quartz in talc. The step increment was 0. 01", 26 with a counting time per step of 50 s e c s ,, an 8 sec. time constant and a chart speed of 1/8 inch per minute. Electron microscopy For electron microscopic examination sam ples of the powder were suspended in isopropanol and lightly ultrasonerateA, A drop of this suspension was placed on carbon coated Nylon gxidB. Examination of the samples was f carried cut in a combined electron-microscope-microprobe-analyzer, EMMA-IV. The samples were examined and photographed at several different magnifications, electron diffraction patterns were obtained from typical fibers present and energy dispersive x-ray analysis was performed on these fibers. RESULTS 1 ) Tight microscopy The following general statements can be made: A ll the samples contained a serpentine which, on the basis of dispersion staining and morphology, has been identified as lizarditc. Chrysotile (the asbestiform variety of serpentine) and antigorite were not detected, i All the samples contain tremolite identified by dispersion staining and [ polarized light microscopy and, although i t would be possible to m iss a small ' percentage of anthophyllite particles,since most antliophyllites give nearly the same dispersion staining colors as tremolite, appreciable amounts of anthophyllite would not be m issed because a significant number of particles would Lie in the proper orientation for positive identification. With the exception of an occasional particle in Sample 83757, all the particles which showed the trem olite/ anthophyllite dispersion colors showed oblique extinction under crossed polars (y Ac = 17-18"), thus identifying them as tremolite. ,,, waiter em c crone associates, inc. T T T T A ll samples contain talc in a form which looks like fibers. These give typical talc colors by dispersion staining. The majority of these talc fibers are apparently long talc rods. These talc fibers are especially long in Sample 8375 __ Most samples are believed to contain a little quartz on the b asis of the light microscopical examination, It is difficult to put an accurate value to the amount of quartz present, since it is extremely difficult to distinguish between quartz and lizardite under dispersion staining conditions. A calculation o f the percentage of amphibole present and of the portion of this amphibole which was fibrous was made as follows. First the portion by volume of the total tremolite present as fib eis was estimated taking cognizance of both particle size and numbers present.. Subsequently, 30 fields in each sample were examined in detail and1the percentage by area o f the total particle area occupied by amphibole particles was estimated. Table 1 summarizes the observations made by light microscopy. X-ray diffraction All samples showed the presence of talc, an amphibole and a serpentine. Inconclusive evidence of quartz was detected by x-ray diffraction on the normal scan. By step scanning, however, low levels of quartz were found. The quartz data are presented in Table 2 and Figure 1. The serpentine minerals are difficult to distinguish from each other by x-ray diffraction. A paper by Mumpton^ indicates certain lines which may f be used to distinguish the three serpentine polymorphs provided that the samples are relatively monominerallie. Specifically, Mumpton mentions that lizardite is characterized by a strong doublet at 1.531 A. This doublet has indeed been observed on our x-ray diffraction trace, thereby confirming the light microscopical' identification of lizardite by dispersion staining. Characterization of ch rv so tile a sb esto s and oth er m em b ers oi the s e r p entine group o f m inerals, Siem ens review X U (1374) 7th sp ecial issu e , X -ra y and Electron Microscopy Sew s. ,,, waiter c. mecrone associates, inc. T T T ( Sample Table I Summary o f Light Microscopical Data 83755 JJ' 83756 3* 83757 _^ 5 83758 _X _ 83759 .F 83760 83761 Total tremolite {%of sample by area) 25-30 Fibrous tremolite (estimated % by vol. of total tremolite) 5 Quartz + Serpentine + Talc "fibers" (rolls, shards .etc.J + Comments 15-20 20-25 . / * 25 8-10 # possible , + ? '- 25-30 5 + +? 25-30 15-20 25-30 1 25 10 - ? . +? +? + probable prcbabl + + + +(long) + large tremolite plates large particle size sm all particle size f l K* ?L l I 19 T T J i i I Sample Quartz Content** Content tremolite Table H Tremolite and Quantity Content of Talc Samples ./* . f . 83755 83756 83757 83753 83759 83760 83761 2% 1/2-1% - 1 1 /2 % ~ 1 1/2% <1/2% below 1/2-1% u * detection lim it 40-50% 50-80%*? 40-50%* '60% >50-60%* 50-60% 40-50% Step scanning data. it Indicates possible anthopbyHit e present in addition to trem olite. 20 T T T T This leaves only the amphibole to be characterized in uU seven The primary amphibole observed is tremolite. The diffraction ved arc consistent with ASTM Card 13-437 for tremolite and with, ata for tremolites from the Gouverneur district. In one sample, ample 83757, a distinct side peak on the tremolite 8.410 line is id it is believed that this side peak i s due to the presence of some :e. Less distinct evidence of this side peak is also present on 50 and possibly also 83759 (see Figures 2-8 for a comparison of 28 range on these sam ples). As is clear from these figures, tn the side peak attributed to- anthophyllite there is considerable i the ratio of talc to amphibole in these samples. An attempt to his relationship in terms* of percentage of amphibole present is also ble 2. :on microscopical examination. Electron microscopical examination shoned that all seven samples stantiai amounts of fibrous material- This was highest in Sample .owest for Samples 83756 and 83761. Several typical electron m icrowing general areas of the samples are appended to this report -17). The electron m icroscopical examination concentrated o r the terial and an attempt-was made to estimate how much of this material asbestiform, that is , a fibrous amphibole as distinct from the fiber dc consisting of ribbons, shards, rolls, etc. This examination was 30th by electron diffraction and by elemental analysis using energy x-ray. The results of these examinations are summarized in Table 3, ited percentages being based on occluded area. Seme typical electror hs, diffraction patterns and energy dispersive x -ra y spectra are hi none of these fibers examined was there a particularly highpercalcium noted; however, calcium was observed at the level of the -3% in all the amphibole fibers examined. The only conclusion whichi i rvw* /in r T r T T I Table HI Electron Microscopical Estimates of Fiber Content Sample 83755 Total fibers -10% Fibrous amphi- bole (as %of total sample) <5% 83755 "10% <5% 83757 83758 -40% -30%. 83759 83760 -5-10% -20% 83761 -- 10% 15-20% 10-15% <5% ''v5% <5% t Iii 1 I f i 1 22 T T T a b le IV Overall Data Summary sample 83755 83756 83757 83758 83759 83760 83761 Total ObersfTEM) 10% Amphibole libers1 (TEM) <5% Total amphi bole* (XRD) 40-50% Total amphibole^ (LM) 25-30% Fibrous am phibole4 (LM) ,,Serpenti.n2e, 5 (XRD) 1-2% 10-15% Quartz2 ,6 (5. S. X-RD) 2% 10% <5% / 50-60% 15-20% 3-5% 10-15% 2/2-1% 40% * 30% 5-10? 20% 10% * 15-20% 10-15% f 40-50% -60% <5% >50% s% <5% 50-80% . 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% -30% ~ ll/2 % -11/2% <1/2% B .D .L . 1/2-1% NOTES: 1 Based on occluded area 2. Estimated weight percentage 3. Based on occluded area 4. Derived from estimated %o f total amphibole which was fibrous. 5. Identified as lizardite by light microscopy 6. S.S. XRD = Step scanning x-ray diffraction See also Table L 23 1-------------- :-------------- '-------------1-------------- 1----------------------------- T can be drawn from the electron diffraction and energy d isp ersive x-ra y analysis is that one has a fibrous amphibole of the tremolitu or anthophyllite type, It is generally not possiole to distinguish between trem olite and anthophyllite by electre: * 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 m icroscopical examination, however, during which a diligent search was made, particularly on Sample 83757, for fibers which might be anthophyllite rather than trem olite, cne is forced to the conclusion that, rather than being a calcium bearing anthophyllite, the fibers are in fact a low calcium trem olite. The aspect ratios of many of the fibers observed are quite high and numerous fib ers, such as those shown in Figures 20, 22, 24 and 30 showed the c la ssic fibrous structure of the asbestos m inerals. There i? no doubt in our minds that these are indeed asbestos fibers rather than cleavage fragments cf a m ore m a ssiv e amphibole. M assive forms of the amphibole are, however, present and the fibreus amphibole content represents only a fraction of the total amphibole content o f the sam ples. CONCLUSIONS Table 4 sum m arizes 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 m in erals?", the answer m ust be an unequivocal y e s. The asbestos mineral present appears to be a low calcium trem olite and is definitely asbestiform by any definition of the word. The asb estos content in the samples varies from less than5% to approximately 20%, based on occluded areas observed in the transm ission electron m icroscope. Respectfully submitted, Ralph J. Hindi, Jr. Senior Research Scientist Richard J - S l u m p s Research Chemist r Ian M . S t e w a r t M anager, E lectron Optics Croup waiter a me cran e associates, inc. T T T .Jil` T` M* k>.i . HGTOES 1 THROUGH 4G * . EXAMINATION OF TALCS FROM GOTJVERNEUR DISTRICT -- NEW YORK 25 T T T T Figure i Step scanning data for quartz Ululiti Sample 83757 (003)Talc (a -SiC>2+) Sample 83758 (004) Talc (a-S lO ^ ) Sample 83759 (005) Talc (a-SiO^+J Sample 83760 (006) Talc (a-SiO ^ ) Sample 83761 (007) Talc (Q-SiO0+t 26 waiter c. mecrone associates, ine. T T T T 4 0 U i 12 1 1 i i s' l ( I l s v j i il Figure 2 v.v* '.r'rfr? CtFS?:\ X r$ - 60- o 00 O (D O X-RAY DIFFRACTION DATA : Sample No. .......... Project No. ..tf'Q P.P.. 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