Identification of chlorite and serpentine in cosmetic or pharmaceutical talc

Our plain-English summary of Identification of chlorite and serpentine in cosmetic or pharmaceutical talc, by A.M. Blount, A.H. Vassiliou (Environmental Health Perspectives, 1983).

The study

• Authors: A.M. Blount, A.H. Vassiliou
• Journal: Environmental Health Perspectives
• Published: 1983;51:379-85
• Cited by: 1 article, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Chlorite is the most common accessory mineral group found in high purity talc ore used in cosmetic or pharmaceutical consumer talcum products. X-ray diffraction and wet chemical analytical data obtained on geologic samples representing commercial talc ore deposits of high purity and on processed samples representing talc found in consumer talcum products indicate that clinochlore and penninite are the two chlorite minerals most commonly found in all talc samples irrespective of origin or source, but sheridanite is also found in some samples representing talc deposits that are associated with serpentinite rocks. The chlorite minerals exhibit certain well-defined X-ray diffraction characteristics which differentiate them from each other as well as from those of serpentine minerals, including the hazardous chrysotile asbestos.

In plain English

This was a laboratory mineralogy study, not a study of people or disease. The authors examined talc and chlorite samples taken directly from producing talc deposits in Georgia, California, Vermont, Montana, North Carolina, Alabama and Pennsylvania. They also examined talc ore from Italy, Montana, North Carolina and Vermont that had been processed for cosmetic or pharmaceutical talcum products. They used X-ray diffraction, plus wet chemical analysis of three chlorite samples. The aim was to tell chlorite, the most common accessory mineral in high-purity talc, apart from serpentine, which includes chrysotile asbestos, because their main X-ray peaks overlap. Chlorites found with talc had similar X-ray characteristics wherever the talc came from. The four chlorites analyzed (one using published data) were clinochlore and penninite. The authors described step scanning and a three-hour heat treatment to separate chlorite from serpentine. They noted that heating has limits. They also noted that when chlorite is 6% or less of a sample and matches their reference peaks, any serpentine present is below the instrument's detection limit.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Laboratory mineralogical study using X-ray diffraction and wet chemical analysis of talc and chlorite samples
• Who was studied: Mineral samples, not people. "Geologic samples" came from producing talc deposits in Georgia, California, Vermont, Montana, North Carolina, Alabama and Pennsylvania. "Processed samples" came from talc ore from Italy, Montana, North Carolina and Vermont that had been processed for cosmetic or pharmaceutical talcum products. Wet chemical analyses were done on three geologic chlorite samples (Alabama, North Carolina, Pennsylvania), selected from about two dozen chlorite samples from over ten localities. A fourth analysis (Montana) was taken from the literature. No collection dates were given.
• Exposure: No human exposure was studied. The minerals examined were chlorite-group minerals (clinochlore, penninite, sheridanite) in cosmetic and pharmaceutical talc. The study also looked at how to distinguish these from serpentine minerals, including chrysotile asbestos.
• Main results:
  • Chlorites found with talc, in both geologic and processed samples, had similar X-ray diffraction characteristics regardless of where the talc deposit came from.
  • The four chlorites with chemical analyses (three analyzed for this study, one from published data) were clinochlore and penninite. Data from an earlier study by Albee suggested sheridanite as another chlorite type in these deposits.
  • When chlorite made up 6% or less of a sample and its peaks matched the reference data in Table 1, the authors stated the mineral could be identified as chlorite with confidence. Any serpentine present in such cases would be below the diffractometer's detection limit.
  • Heating an oriented sample for three hours made the 7 and 3.5 angstrom peaks disappear when they belonged to chlorite. The scanned text prints the temperature as "5000C". A peak that remained, slightly shifted, indicated serpentine present along with chlorite.
  • The authors stated that a wider X-ray divergence slit (printed as "30" in the scanned text) loses 72% of the X-ray beam. This can make the characteristic chlorite peak disappear, so chlorite could be mistaken for serpentine when no serpentine is present.
• The authors' conclusion: The authors concluded that chlorites from talc deposits and from processed cosmetic-grade talc are quite similar in X-ray diffraction characteristics and chemical composition, whatever the origin of the deposit. They concluded that the most applicable reference patterns for identifying chlorite in talc are those of clinochlore, penninite and sheridanite.
• Limitations the authors state:
  • The heat treatment technique is limited because some serpentine loses intensity in its basal reflections before reaching its decomposition temperature. The scanned text prints that temperature as "6000C".
  • When chlorite is 6% or less of a sample and its peaks show no distortions, serpentine below the detection limit will not be detected, even with special treatments.
  • In one processed talc sample, the chlorite was at the detection limit of the X-ray procedure, so peak intensity and position were hard to measure accurately (experimental error).

Topics

The National Library of Medicine indexes this study under subjects our site covers: Talc and vermiculite.

Medical terms in this study, explained in our Lexicon: Chlorite, Serpentine Group, Talc, Accessory Mineral, X-Ray Diffraction (XRD), Serpentinite, Chrysotile.

Related studies

• Evaluation by electron microscopy techniques of asbestos contamination in industrial, cosmetic, and pharmaceutical talcs — L. Paoletti, S. Caiazza, et al. (1984)
• Amphibole content of cosmetic and pharmaceutical talcs — A.M. Blount (1991)
• Cosmetic talc and ovarian cancer — D.L. Longo, R.C. Young (1979)
• Mesothelioma Associated With the Use of Cosmetic Talc — J. Moline, K. Bevilacqua, et al. (2020)
• Cosmetic talc as a risk factor for pleural mesothelioma: a weight of evidence evaluation of the epidemiology — B.L. Finley, S.M. Benson, et al. (2017)
• Serous Ovarian Cancer Caused by Exposure to Asbestos and Fibrous Talc in Cosmetic Talc Powders-A Case Series — J.E. Steffen, T. Tran, et al. (2020)

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