POT'STONE, noun potstone appears to be indurated black talck, passing into serpentine. It has a curved and undulatingly lamellar structure, passing into slaty. Potstone is of a greenish gray color. It occurs massive, or in granular concretions. Potstone is a variety of steatite.
Source: Webster's 1828 American Dictionary ↗ · public-domain · returned verbatim, no AI