The Encyclopedia Americana (1920)/Auerlite

AUERLITE, a rare North Carolina mineral, remarkably rich in thoria, named after Dr. Carl Auer von Welsbach, the inventor of the Welsbach incandescent gas mantel. It was originally described as a hydrous silico-phosphate of thorium, ThO$2$(SiO$2$, ⅓P$2$O$5$)+2H$2$O. It occurs in yellowish, zircon-like crystals of resinous lustre and having a hardness of 2.5 to 3 and a specific gravity to 4.1 to 4.7.