The record
USGS Bulletin 1082-K documents that amphibole asbestos was known to occur in Baltimore and Cecil Counties, Md., as early as 1837 (citing Ducatel, 1839, p. 5), and states at p. 803 that 'the amphibole deposits are almost all closely associated with talc' — adding that talc quarries at Dublin, Md., and Gladwyne, Pa., 'produced some asbestos as a byproduct.'
Claim scope
The early history of American talc mining and the primary-source geological association between amphibole minerals and talc deposits.
What this source does not establish
The 1837 anchor is about ASBESTOS, not talc mining — do not describe 1837 as a talc-mining date. Cite 'Ducatel, 1839, p. 5' (the report covering 1838) as the bulletin does. The geological association does not establish that any specific commercial talc product contained amphibole asbestos.
Limitations
The p. 803 sentence is the primary anchor for the geology section; quote it directly.
Source
Gov Report — USGS Bulletin 1082-K (Pearre & Heyl, 1960), pp. 801-803 — asbestos production history at p. 802, geologic occurrence at p. 803; bibliography entries for Ducatel J.T., 1838/1839/1840 annual reports of the geologist of Maryland