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' PITFALLS IN RAY DIFFRACTION METHODS OF ANALYSIS FOR IMPURITIEISN TALC POWDERS Jerome B. Krause CSM Research Institute Golden Colorado William H. Ashton Johnson & Johnson Raritan New Jersey PRESENTATION AT DENVER COLORADO APRIL 26 1977 SYMPOSIUM ON ENVIRONMENTAL & OCCUPATIONAL HEALTH ANALYSES Protected Document to Protective Order JNJ 000090165 ; PITFALLS IN RAY DIFFRACTION METHODS OF ANALYSIS FOR IMPURITIES IN TALC POWDERS Jerome B. Krause CSM Research Institute , Golden Colorado William H. Ashton Johnson & Johnson Raritan New Jersey | @ PRESENTATION -- -- DENVER , COLORADO APRIL 26,1977 " | ' . SYMPOSIUM ON .- -. | ENVIRONMENTAL ' & OCCUPATIONAL HEALTH ANALYSES 8 8 9 Protected Document to Protective Order DRAFT Final DRAFT Final DRAFT DRAFT * JNJ 000090166 @ PITFALLS IN RAY DIFFRACTION METHODS OF ANALYSIS . FOR IMPURITIES IN TALC POWDERS Jerome B. Krause CSM Research Institute Golden Colorado William H. Ashton Johnson & Johnson Raritan New Jersey * @ As we are all aware the current high interest in potential and real health hazards of asbestos has resulted in a great number of investigations dealing with the isolation and identification of asbestos from a tremendous variety of manufactured natural and product materials One effect | of the great attention being given to asbestos minerals is to convey the erroneous impression that the predominant occurrence of serpentines and amphiboles are as the asbestos varieties Rather special geological con- ditions seem to be required to produce asbestos Vermaas 1952 and it is fact that less than % of the world occurrences of serpentines and amphiboles are as the asbestos varieties Thompson 1973 Ampian 1976 | INTERPRETATION ERRORS Since asbestos is in fact somewhat rare it is important to be cer- tain that the identification of asbestos in a sample is correct Certain pitfalls in the identification of asbestos and other minerals have become apparent as follows Powder ray diffractometry is incapable of determining the mor- phological variety of a mineral For example examination of a powder ray diffractogram of essentially pure serpentine cannot unequivocally identify the sample to be a particular morphological variety Preparation Protected Document to Protective Order , . ; JNJ 000090167 r @ @ @ -2- of synthetic calibration standards using asbestos and talc for example has the tendency to bias the interpretation when analyzing real samples Examination of ray diffraction photographs of the tiniest asbestos fiber that can be handled shows that the pattern is streaked indicating that the smallest fiber is still composed of multiple crystals oriented with slight displacements around the fiber axis Hutchinson et al 1975 | Chisholm 1973 Thus single crystal ray diffraction does give some information as to whether or not the specimen could be asbestos Amphiboles The amphibole family of minerals is characterized by similar crystal structure and wide variation in chemical composition and appearance The name is derived from the Greek amphibolos meaning ambiguous a most appropriate name since reliable identification of members of the group is indeed difficult All amphiboles have ray diffraction patterns which are similar and are characterized by having their 110 110 or 210 diffraction peaks within 0.2^ of each other Table ) Selection of JCPDS Card No. 13-437 for tremolite 110 == 8.38= 10.56 20 for Cuka as being representative and definitive for identification and quantification of that mineral presents problems which become apparent with examination of Table 1. Twenty different JCPDS amphiboles have their 110 or 210 peaks within 0.1 20 of this tremolite 110 peak Identification of an amphibole as being tremolite on the basis of a peak at 10.56 20 obviously is an identification with very low reliability With further examination of Table 1 it becomes apparent that attempted Protected Document to Protective Order ! ~ 000090168 @ ;) @ -3- identification of any amphibole on the basis of 110 or 210 has great potential for being in error 1 TABLE Amphibole JCPDS Card No's 110 or 210 Peak Position and Relative Intensity JCPDS . Card # R 28 Cu 23-118 10-456 20-734 20-378 14-633 21-149 19-467 20-982 23-665 23-664 23-667 23-663 9-434 13-499 20-656 20-470 23-666 20-469 23-1405 23-1406 10-428 23-603 10-431 19-1061 20-481 8.58 10.31 8.55 10.35 8.53 10.37 8.52 10.38 8.51 10.39 8.51 10.39 8.50 10.41 8.50 10.41 8.48 10.43 8.47 8.47 10.44 10.44 8.46 10.46 8.45 10.47 8.45 10.47 8.45 8.44 10.47 10.48 8.44 10.48 8.43 10.49 8.43 10.49 8.43 8.42 10.49 10.51 8.42 10.51 8.41 10.52 8.40 10.53 8.40 10.53 JCPDS I Card # ^ 20 Cu I 100 100 70 100 70 55 100 65 45 35 45 40 50 100 100 100 40 100 80 40 100 100 80 100 100 20-1390 8.40 10.53 90 23-302 8.40 10.53 100 19-1063 13-437 8.39 8.38 10.54 10.56 70 100 17-478 8.38 10.56 65 23-495 9-330 8.38 8.37 17-750 8.36 20-386 8.35 10.56 10.57 10.58 10.59 80 100 25 40 22-531 8.35 10.59 30 16-401 8.33 10.62 70 17-725 17-745 8.33 8.33 10.62 10.62 100 100 20-376 17-726 8.31 8.30 10.65 10.66 100 100 20-484 8.29 10.67 100 13-506 8.27 10.70 80 23-679 8.27 10.70 90 9-455 8.26 10.71 55 20-453 11-253 8.26 8.23 10.71 10.75 100 100 20-1310 8.20 10.79 75 23-310 8.20 10.79 75 13-401 8.11 10.91 . 100 MaximumA 20 Cu = - 10.91 = 10.31 0.6 Problems further affecting the reliability of amphibole identification are the effects of shift in peak position caused by mispositioning of the sample surface and method of interpretation of the peak position e.g. centroid or maxima The overall significance of 110 210 peak - Protected Document to Protective Order JNJ 000090169 c.. @ @ @ | -4- position is that it can be used to do no more than to generally eliminate certain amphiboles from further consideration as being present Single Peak Identification Implicit in the preceding discussion is the potential hazard assoc- iated with identification of a phase on the basis of a single diffraction peak An example of erroneous single peak identifications is presented in a paper by Snider et al 1972. Of 18 commercial talcum powders examined by these authors they reported the XRD identification of anhydrite in 15 serpentine in 13 clay in 17 actinolite in 9 and anthophyllite in 6. Chlorite one of the most common accessory minerals found associ- samples clay ated with talc was not identified in any of the although their | may in fact be chlorite We have examined some of the identical samples reported on by agree Snider et al and cannot with their interpretations of anhydrite . serpentine and tremolite anthophyllite We can only conclude that the erroneous identifications presented by Snider et al , were made on the basis of single diffraction peaks without any real consideration of | potential errors in their identifications Abnormal Crystal Habit In a detailed examination of a commercial talc sample a minute amount of acicular mineral which appeared to be amphibole was isolated However subsequent detailed examination by Gandolfi XRD of five hand- picked grains all 150 ...mlong identified talc without evidence of any amphibole being present Careful optical examination in oil immersion . Protected Document to Protective Order a . JNJ 000090170 . . | -5- media with determination of indices of refraction and extinction angles confirmed the XRD identification of talc as being correct ray diffraction examination of a different sample of industrial bulk acicular talc revealed the presence of significant amphibole probably tremolite Careful optical examination of this sample showed it to be composed of free grainosf acicular talc and columnar amphibole and composite amphibole grains The talc appears to be pseudomorphic after amphibole and its unusual acicular habit is likely derived from its amphibole pseudomorph This occurrence shows an important pitfall where one mineral talc can be misidentified as a different mineral tremolite and cause the wrong conclusion to be drawn | INTERFERENCE ERRORS fi Serpentine It is well known that chlorite and serpentine are difficult to dif- ferentiate by all known methods of characterization Generally Generally however the 004 XRD peaks are separate enough to allow unambiguous identification of both phases when present in amounts sufficient to give definable peaks . Serpentine and chlorite XRD patterns are usually characterized by broad peaks which are often poorly defined and resolved especially when present in minor amount A situation somewhat similar to that for amphiboles exists for serpentine and chlorites e.g. similar crystal structure and wide vari- ation in chemical composition As a result the diagnostic chlorite 004 peak and serpentine 004 0012 or 002 peak shows considerable variation in the position in which it occurs Tables 2 and 3 The observed Protected Document to Protective Order . ; JNJ 000090171 ) -6- TABLE 2 Chlorite JCPDS Card No's 004 Peak Positions and Relative Intensity JCPDS Card # ^ 20 Cu Name 10-183 20-671 . 16-351 - 12-185 7-160 ' 19-749 7-77 16-362 19-751 22-712 7-165 7-78 7-171 12-242 7-76 12-243 21-1227 3-67 3.60 3.60 3.59 3.57 3.58 3.56 3.558 3.55 3.55 3.55 3.545 3.541 3.541 3.54 3.537 3.53 3.523 3.52 3.52 3.49 24.73 24.73 24.80 24.94 24.87 25.01 25.03 25.08 25.08 25.08 25.12 25.15 25.15 | 25.16 25.18 25.23 25.28 25.30 25.30 25.52 100 100 penninite k^/mmererite chlorite lb kotschubeite kotschubeite ~ clinochlore sheridanite chlorite la sudoite nimite grochauite thuringite diabantite leuchtenbergite ripidolite thuringite daphnite aphrosiderite thuringite thuringite | 115 wide variation in peak positions shown in Tables 2 and 3 demonstrates the need for every sample to be considered on an individual basis The se- > lection of peaks at 3.65^ and 3.55 as definitive of serpentine and chlorite respectively can certainly result in erroneous identifications Chlorite is a very common accessory mineral associated with - talc whereas serpentine is much less common When serpentine is present it typically is at a much lower concentration level than chlorite Quantification of minor to trace serpentine in the presence of at least equivalent amounts of chlorite is an extremely difficult if not impossible " Protected Document to Protective Order JNJ 000090172 ( .@ -@ 7- 3 TABLE ; Serpentine Kaolinite Halloysite and Dickite JCPDS Card No's Peak Position Miller Index hkl and Relative Intensity JCPDS | Card ^ 28 Cu I hkl | Serpentines 18-779 9-444 - 21-543 7-417 11-386 21-963 12-583 13-4 7-339 11-388 7-315 9-493 - 3.67 3.66 3.65 3.63 3.62 3.61 3.56 3.56 3.55 3.55 3.52 3.52 . 6-221 14-164 12-447 | 3.58 3.579 3.56 9-453 3.63 10-446 3.58 24.25 . 24.32 24.39 24.52 24.59 24.66 25.01 25.01 25.08 25.08 25.30 25.30 80 100 70 300 - 60 80 . 80 70 100 100 100 100 002 0012 ' 004 102 002 002 0012 0012 002 0012 002 004 lizardite 1M antigorite 60 ~ chrysotile 2M antigorite 6M lizardite 10 aluminan antigorite antigorite antigorite 6M 60 60 aluminan aluminan berthierine antigorite 60 syn berthierine amesite | Kaolinites 24.87 24.88 25.01 100+ 80 50 002 002 002 kaolinite kaolinite kaolinite 1Md 1T 1T Halloysite 24.52 90 002 halloysite dehydrated 24.87 100+ Chlorite 20 Range Dickite 004 _ = dickite 2M^ 24.73 - 25.52 task Stanley and Norwood 1973 for example state that chlorite must be absent in order to quantify level serpentine by XRD An example of erroneous identification and quantification of ser- | pentine in talc occurred in 1972 where 2.9 serpentine was identified in a talc sample on the basis of two XRD peaks at 12.28 20 7.21^ and 12.05 7.34^ misinterpreted as chlorite and serpentine respectively In con- trast our examination of this sample Caneer W. T. 1977 identified - Protected Document to Protective Order , JNJ 000090173 o @ @ peaks at 1^ and 7.22^ of Examination the 14 region identified first- order equivalents of these peaks at 14. 1^ and 14.47^ respectively Ex- amination of the 3.5 region identified fourth equivalent peaks at 3.54^ and 3.61^ respectively Since serpentine does not have a 14^ peak the double peaks in the regions of 14^ 7^ and 3.5 are almost surely due to two chlorites possibly thuringite and penninite rather than chlorite and serpentine If any of the three clay minerals kaolinite halloysite or dickite are present they will interfere in the same way as does chlorite Distinction between serpentine and kaolinite halloysite or dickite is extremely difficult however since unlike chlorite these minerals minerals do not have a peak in the 14 region that clearly distinguishes them from serpentine The data of Table 3 shows the severe nature of interference with serpentine | of the kaolinite halloysite dickite 002 or 004 peaks Talc Quartz Quartz is often found as a level accessory mineral occurring with talc Identification and quantification of quartz by XRD is a relatively straightforward analysis but problems do exist For example Rohl et al 1976 analyzed a number of talcums for quartz by XRD using the relatively weak 211 quartz peak I = 15 at 1.54 60.08 20 for Cuka However the strong 060 talc peak I = 55 at 1.53 60.51 20 for Cuka will overlap and mask the presence of small amounts of quartz Trace to minor amounts of quartz in the presence of major talc clearly cannot be quantified on the basis of 211 intensity We suggest that 101 the Protected nO . Document to Protective Order , 7 ; JNJ 000090174 @ .@ @ -9- most intense quartz peak is generally free from interference and is best used for identification and quantification of quartz CFTA Method J 6-1 METHODS FOR ELIMINATION OF INTERFERENCE . AND INTERPRETATION PROBLEMS Simple awareness of interpretation and specific interference errors is often effective in prevention of their occurrence ' However solution of the problems surely requires more than to simply know of their existence Specifically we have applied techniques involving separation and isolation of the phases of interest followed by standard and special XRD techniques and confirmatory optical microscopy and microprobe analysis as required Handpicking Handpicking A very effective method of isolating minerals for analysis is that of handpicking The optical microscope is an extremely sensitive analytical tool capable of detecting impurities at a very low level However optical identification of a detected impurity can be difficult and handpicking for XRD identification is a possible confirming method The identification of acicular talc described earlier was performed in this manner e.g. , de- - tection by optical microscopy followed by handpicking Gandolfi XRD and finally determination of confirming optical properties The Gandolfi XRD method has a number of advantages as follows ' 1 A powder pattern will be produced from a single crystal as small as about 30 ...m es 2 The sample is not crushed and thus is available for examination by optical microscopy or microprobe 3 The sample is normally composed of only one phase whereas larger samples increase the chance for introduction of additional phases Protected Document to Protective Order ; 4 JNJ 000090175 La -10- 4 The diffraction pattern obtained is usually very sharp This is due - 6 broadening to the very small sample size and the lack of line grinding deformation from Density Gradient Column Heavy Liquid Separation The density gradient column is an apparatus that can produce very delicate specific gravity separations Muller and Burton 1965 Smale 1970 The method operates by introducing a sample into a column of liquid that is continuously variable in specific gravity high specific gravity at the bottom to low specific gravity at the top The components of the sample settle to the level of their specific gravity and are removed by the ; extraction apparatus The method has the ability to separate two minerals having a in difference specific gravity as small as 0.003 For example we ' . have separated a chloritic talc powder into three fractions by this method XRD and optical examination of the fractions indicated that the fractions were talc chlorite and locked talc plus chlorite SUMMARY In summary we have discussed specific interpretation and inter- ference pitfalls commonly encountered in the routine examination of talc powders These included The inability identify amphibole species on the basis of 110 d or 210 chlorite serpentine and quartz interferences identifications based on one peak and talc with amphibole morphology e.g. amphibole pseudomorphs Isolation of mineral species by handpicking and density gradient @ separation have been suggested as aids in reducing some interference and interpretation problems Gandolfi XRD and optical microscopy were pre- sented as sensitive analytical methods i Protected Document to Protective Order 1 , ; . JNJ 000090176 & :@ -11- REFERENCES Ampian S. G. 1976 Asbestos minerals and their nonasbestos analogs Mineral Fibers Session Electron Microscopy of Microfibers Symposium Penn State Univ August 1976 Caneer W. T. 1977 C.S.M.R.I. personal communication Chisholm J. E. 1973 Planar defects in fibrous amphiboles Materials Sci vol 8 pp 475-483 Jour of CFTA Specifications on Cosmetic Talc 1976 Cosmetic Toiletry and Fragrance Association Inc. 1133 15th St. Washington C. 20005 Hutchinson J. L. Irusteta M. C. and Whittaker E. J. W. 1975 resolution electron microscopy and diffraction studies of fibrous amphiboles Acta Cryst vol A31 pp 794-801 Muller L. D. and Burton C. J. 1965 The heavy liquid density gradient and its applications in ore dressing mineralogy Eighth Commonwealth Mining and Metallurgical Congress Australia and New Zealand vol 6 general proceedings Paper 49 pp 1151-1163 Rohl A. N. Langer A. M. Selikoff I. J. Tordini A. Klimentidis R. Bowes D. R. and Skinner D. L. 1976 Consumer talcums and powders mineral and chemical characterization Jour of Toxicology and Environmental Health vol 2 pp 255-284 Smale D. 1970 gradient columns with special reference to their application to model analysis Minerals Science and Engineering vol 2 No. 2 pp 18-23 Snider D. W. Pfeiffer D. E. and Mancuso impurities in commercial talcum powders Epsilon vol 49 pp 65-67 J. J. 1972 Asbestos Compass of Sigma Gamma Stanley H. D. of asbestos Report and Norwood R. E. 1973 The detection and asbestiform materials in talc Pfizer and identification Inc. Company , Thompson C. S. 1974 Discussion of the mineralogy of industrial talcs U. S. Bureau of Mines Information Circular 8639 Proceedings of the Symposium on Talc Washington D. C. May 8 1973 Vermaas F. H. S. 1952 The amphibole asbestos of South Africa Transactions and Proceedings of the Geological Society of South Africa vol 55 pp 199-229 , Protected Document to Protective Order . JNJ 000090177