Gems Notes and Extracts Augusto Castellani, Mrs. John Brogden 1871

AMETHYST. 33VIIITHE AMETHYST.THE amethyst, like all gems, is both Oriental andWestern.The Oriental amethystis a clear corundum of a violetcolour, somewhat reddish and of an elegant velvetlikeappearance ; very bright ; perhapsless hard thanthe ruby ; specific gravity 4 ;of weak double refraction;and it cuts deeply into the rock crystal. TheWestern amethyst can be distinguished from it by thefact that when rubbed it preserves vitreous electricitybut twenty or thirty minutes, whereas the Orientalpreserves it for many hours.The Western 'amethyst is a clear quartz, colouredviolet by the oxide of manganese which it contains :of the specific gravity of 2*7, it crystallizes in the formof a hexagon, terminated at the two heads by a speciesof cone with six facets. These crystals are often inmasses, and the base isalwaysless coloured than thetop. The cleavage in one of such masses appearsfibrous and concave in crystals of small size. Thecolour is more or less dark, and does not resist fire.This gem possesses double refraction, but in a moderatedegree.It is motionless under the magnetic needle.It may be remarked that amethysts are generallyfound in metalliferous mountains, and are always incombination with quartz and agate.This substance isfound in Ceylon, Siberia, Kamtschatka, Arabia, Brazil,D