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Elongate mineral particles, including asbestos, have long been screened in talc and other mineral powders. In recent years, there has been a renewed scrutiny of talc containing asbestos due to allegations in civil litigation in the United States as well as reports, proposals, and white papers by international laboratories and government bodies related to this subject. This study demonstrates the importance of the fundamental understanding of both mineralogy and its application, using microscopy with empirical examples from conflicting analyses of the same talc powders by two independent laboratories in civil litigation in the United States. Methods include polarized light microscopy (PLM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) in the accurate measurement of morphological, optical, compositional, and structural data to characterize mineral-based samples. Discussions in this study include: 1) contrasting the interlaboratory findings of amphibole and amphibole asbestos by PLM and TEM using various preparation techniques, 2) the use of multiple analytical tools on a singular particle for identification, 3) the misidentification of anthophyllite asbestos by inexpert use of electron diffraction using TEM, and 4) the misidentification of chrysotile in talc by PLM. These examples emphasize the importance of not only maintaining the existing requirements, but of the need for even more rigorous analytical requirements in routine monitoring of elongate mineral particles that may occur in mineral-based powders., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: The samples that were analyzed by the two laboratories discussed above were made available to both labs in the course of civil litigation where the allegation was made by plaintiffs' that the talcum powder product both contained asbestos, and use of product was wholly or at least in part responsible for an individual's mesothelioma. As it is strictly not the purpose of this paper to get into the legal issues only the data sets provided by both laboratories and how methods were applied are discussed and expounded. Both the identity of the product and the other laboratory will not be disclosed, I invite them upon review of this manuscript to make themselves known and expand where appropriate any errors and misrepresentations on my part. I have attempted to present the approaches and deviations from methodologies accurately and how these issues affect interpretation of results by both laboratories. I undoubtably will have either missed a fact or point of emphasis that the other Lab will wish to clarify. I will disclose that Laboratory B is the RJ Lee Group where I am an employee and work as a consultant and expert witness in litigation where the allegation is the presence of asbestos in talc. The data sets for Lab B were all generated under my direction at the RJ Lee Group and were paid for by the defendant in the litigation at the time of analysis. However, I have not received, nor the RJ Lee Group, any funding or reimbursement for the time and effort to publish these results. Further the conclusions reached are my own and do not represent the views of any entity including the RJ Lee Group or said client. No one from that client or any attorney reviewed or had any input in the drafting of this manuscript., (Copyright © 2022. Published by Elsevier Inc.)