Mid 19th century; earliest use found in James Dana (1813–1895), geologist, zoologist, and teacher. After German Pyrauxit; so called because it swells when heated.
Definition of pyrauxite in US English:
pyrauxite
noun
Mineralogy rare
= pyrophyllite.
Origin
Mid 19th century; earliest use found in James Dana (1813–1895), geologist, zoologist, and teacher. After German Pyrauxit; so called because it swells when heated.