AL'LOPHANE, noun [Gr. other and to appear.] A mineral of a blue, and sometimes of a green or brown color, which occurs massive, or in imitative shapes. It gelatinizes in acids. Allophane is a variety of clay, occurring in amorphous, botryoidal or reniform masses.
Source: Webster's 1828 American Dictionary ↗ · public-domain · returned verbatim, no AI