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5) a tod ag ra tod Bo te ae " 567 OM " 3 7 yw 13 oO G10 >' 15 15 11 10 - 13 - TEH TEH 198 LETTER TO THE EDITOR CHCAHARRACATECRIZTAtEionRIZAtion MINERALOGICAL MINERALOGICAL HENTICATION HENTICATION ae OF COSMCETOISC MTETaItCeTALC PRODUCTS.- of this letter is to comment on the paper by Rohl et al entiTtlheed pCuornpossuemer Talcums and Powders Mineral and Chemical Char- acterization which appeared in the Journal of Toxicology and Environ- bee) mental Health 255-284 1976 H i] be Q i H The paper conveys an erroneous impression that it is reasonably of asbestos in counter talcum te OS common to detect the presence 328929825802 328929825802 tat powders The authors imply in fact that half of the products studied otk questionable 328929825802 328929825802 _ 328929825802 328929825802 e . are of quality when they state that 10 of the 20 products 328929825802 32892825802 examined contained detectable amounts of tremolite and anthophyllite 3289 2580 article 332222328828999222982995888022255880022 prinTcihpeally asbisemsitslieading and its publicatidonemdeamnadndss clarcilfairciaftiicoantio inn comprehensive 3289293822528082929825802 light of the following points 1 a understanding of 328929825802 mineralogy makes it apparent that the reported results are impossible to 3289 502328929825802 achieve 2 the analytical methods described do not and can not lead 328929825802 328929825802 to the conclusions reported and 3 the conclusions drawn are without 3228929825802 3228929825802 328929825802 sound scientific basis and are therefore misleading and invalid These 328929825802 points are discussed below ; The portions of the paper by Rohl et al that describe the geologic occurrences and properties of talc and associated minerals are generally correct with one major exception The paper very clearly makes the point that the predominant occurrences of tremolite anthophyllite and as the asbestiform varieties and readers other than serpentine are almost surely reach the professional geologists or mineralogists will erroneous conclusion that occurrences of the asbestiform varieties are the rule rather than the exception It is a fact that the asbestiform varieties of these minerals are relatively rare and that such occurrences probably account for less than % of the known world occurrences of each mineral Further tremolite and anthophyllite are erroneously stated to have fibrous cleavage whereas in fact their cleavage is prismatic Tremolite asbestos is essentially a mineralogical curiosity The analytical methods described by the authors for identification and quantification of tremolite anthophyllite and serpentine are invalid The C01 : i1 Journal of Toxicology and Environmental Health 000-000 1977 Copyright '1977 by Hemisphere Publishing Corporation 0088215 JNJ 000297209 leading lencie leading point point 11 12 - 002 : LETTER TO THE EDITOR aed . oP > tt ar ray diffraction XRD methods described cannot be used to identify the 5 Wim amphibole species present to distinguish serpentine from chlorite or to quantify serpentine or quartz because of interferences from chlorite and 9 8 talc respectively . Unequivocal identification and quantification of the amphibole species vO present on the basis of the tremolite 8.38 ^ 110 peak and the anthophyllite 8.26 ^ 210 peak is impossible Examination of the powder 10 diffraction file published by the Joint Committee on Powder Diffraction JCPDS file | Standards JCPDS for amphiboles 52 amphibole cards in the reveals that all 52 have their 110 or 210 diffraction peaks within ^ of each other For Cuka radiation a change in spacing of 0.2 A at 10.5 14 20 the region step scanned is -11 20 is equivalent to a 20 angular change of only 0.25 Slight compositional and structural variations in the amphiboles readily cause small shifts in the position of the 110 and 210 the peaks Similarly very small changes in the position and nature of the | the sample surface will cause small peak shifts As a result of general re t peak overlap among amphiboles unpredictable peak shifts and mismeasurement of peak position it is not possible to identify any specific amphibole on the basis of the 110 or 210 peak even if the 8C2283 sample is 100 pure amphibole of one variety It is clearly impossible to 8C2283 8C283 identify and quantify trace to minor amphiboles by the methods 8C2283 8C2283 described in this paper Bulk chemical analyses for major minor and trace 24.32 elements has questionable value in the identification of an amphibole 23 23 present in trace to minor amount 24.32 20 for 8C2283 24.30 The authors used the serpentine 004 peak at 3.66 ^ 20 for Cuka for identification of serpentine Chlorite has a major diffraction peak 004 in this region It is well known that chlorite and serpentine are difficult to differentiate by all known methods of characterization but that their 004 XRD peaks are separate enough to generally allow unambiguous determination of the presence of both phases when they are the present in quantities sufficient to give definable peaks However 004 24.71 peak of chlorite varies between 3.53 and 3.60 20 -25.21 for Tat structural Cuka depending on the particular compositional variety present To attempt quantification of trace serpentine in talc by using the 004 peak is not possible since talcs almost invariably contain chlorite far in excess of serpentine and chlorite will therefore interfere The authors - = 24.73 24.73 24.73 -25.27 -25.27 -25.27 acknowledge that Stanley and Norwood were confronted with the chlorite- serpentine interference problem but they still claim to have been able to use XRD for identification and quantification of trace serpentine in the presence of chlorite samples 12 and 15 In addition if any of the clay minerals kaolinite halloysite or dickite . are present they will also interfere with the XRD identification and quantification of serpentine The XRD peaks of serpentine chlorite kaolinite dickite and halloysite are typically broad and often poorly resolved further complicating identification and almost certainly 0088216 JNJ 000297210 kong kong drawing kong point kong 11 we - wm . vou el . OM 72 ie ~w Oo " 1010 12 1 12 21 13 21 14 14 ED 2 2 ee es 2 ca 2283 2283 AD 22283 Pd le 2283 2 83 FQ ew) 22283 22283 "es te 2283 22283 A & Soe 003 EDITOR eliminating any possibility of quantifying trace amounts of serpentine by XRD if any of these interfering phases are present An additional complication is presented by halloysite if it is present 20 Halloysite has a tubular structure similar to that of chrysotile and therefore cannot be distinguished from chrysotile by electron microscopy The authors used the quartz 211 peak at 1.54 ^ 60.02 for Cuka for quantification of quartz in spite of the fact that talc has one large peak and several small peaks in this 20 region that can interfere The problem involves quantification of trace to minor amounts of quartz by using a weak quartz peak 211 relative intensity 15 that is interfered with by a strong talc peak [ 060 relative intensity 55 A recent ray diffractogram of very pure talc run in this laboratory had the angle shoulder of this talc peak extending to 59.7 20 for example completely overlapping the 211 quartz peak position Quantification of trace to minor amounts of quartz on the basis of its 211 peak is clearly not chrysotile possible in the presence of major amounts of talc The interference and identification problems discussed above become when examining errors associated with the linear equations of the afpopramreynt= + bx given by the authors to correlate peak area with percent mineral content table 3 From table 3 comparing the known mineral content with the calculated mineral content using peak areas and equation of fit the error for each data point can be calculated The stated + detection limits 2.0 0.7 1.4 and 0.1 for anthophyllite quartz and tremolite respectively have very little meaning when the The detection limits of 2 and errors for each data point are examined - 1.4 for anthophyllite and quartz are less than the lowest standard prepared % and are therefore strictly theoretical rather than observed ' Using the authors calibration equation for the quartz the calculated value for the % standard an overestimation of the true level by 56 At the stated detection levels for chrysotile and tremolite 0.7 and 0.1 respec- tively the calculated values from the calibration equations are over- estimations of the true levels by at least 100 for chrysotile and 500 for tremolite calibrations for these types of samples and concentration are not ordinarily expected and the use of linear equations to fit ranges the data is questionable especially in view of the previous discussion of interferences and invalid procedures For example the data for chrysotile are distinctly nonlinear figure 2 but the authors still use a linear . equation to fit the data I also wish to point out that the quotation from the paper by Stanley and Norwood is a paraphrase rather than a direct quotation Also there is an error in the quoted fiber size of 0.5 ^ 0.2 mrequiring transmission electron microscopy size stated by Stanley and Norwood is 0.5 ^ 0.02 m The entire paper reflects a strong bias to assume and amphibole minerals are asbestiform The fact that that all serpentine the authors added 6 0088217 JNJ 000297211 leading leating leading point point point 1 11 = ? won 105 82857 10 8257825782857 8285782857 leading leading point point 12 12 | os td wn Ws & ie , , ' a On Oo op 11 12 Me ew ur ee 17 13 13 19 004 LETTER TO THE EDITOR : . . - i asbestos minerals to talc in the preparation of their standards is by no means an assurance that the samples later examined also contained asbestos Use of such standards has the effect of prejudging the samples before they are ever examined and in this case has led to impossible results and invalid conclusions In the above discussion I have described some of the errors and invalid procedures of mineralogical identification and quantification as used by the authors It is therefore apparent that the stated major purpose of their namely to determine the mineralogical and chemical paper composition with particular emphasis on the quantitative determination of tremolite anthophyllite serpentine minerals and quartz has not been achieved Accordingly the results reported are without analytical basis and the conclusions drawn are invalid and misleading Jerome B. Krause Colorado School of Mines Research Institute Golden Colorado i Hy 1 \ $ 4 } i 20222683 202683 i 20 268320222683 & 88 ** we sem 0088218 JNJ 000297212