This case involves a number of individuals who were exposed to asbestos fibers from the use of agricultural talc, which was allegedly contaminated with asbestos fibers. The talc was supplied by a mining company which mined the talc in the northeastern United States. Geological testing at the mine has revealed that the talc develops next to deposits of asbestos fibers, which were allegedly mined incidentally along with talc. As a result, talc sold by this producer was allegedly contaminated with dangerous asbestos fibers.
Question(s) For Expert Witness
- 1. Please describe your geological experience as it pertains to talc and asbestos.
- 2. Can you explain how and why talc develops next to, or interspersed with, deposits of asbestos-containing rocks?
- 3. Can you distinguish between talc and asbestos fibers?
Expert Witness Response E-080977
I have taught mineralogy for decades and have been visiting numerous talc mines on geological field trips since 1972. Mineral assemblages do not always form at a fixed and immutable set of environmental parameters of pressure, temperature, fluid composition, chemical fluxes, time and stability. Hence, in a dynamic metamorphic scenario, it is expected that unstable mineral assemblages are preserved with stable assemblages. For example, talc can be the primary mineral, but tremolite or anthophyllite can be found as a result of prograde (up-temperature) or retrograde (down- temperature) processes. Additionally, fluxes in chemicals and fluids (water and carbon dioxide) can produce mixed assemblages. Lastly, remnant (or, transitional) talc-anthophyllite (talcboles) can occur in talc ores. And locally within a given deposit, local variations in chemistry and deformation can produce mixed talc-anthophyllite-tremolite assemblages. I am very familiar with the standard and the state-of-the art techniques used to characterize asbestos and talc.