Gothite

Gothite (named after the poet Goethe (q.v.) in his less well-known capacity of Director-general of the mines of Saxe-Weimar) is a hydrous peroxide of iron, containing about 10 per cent. of water, which occurs in transparent red crystals of the Prismatic system, but, more commonly, opaque and yellow or brown. Its hardness is 5 to 5'5 and its specific gravity 3-8 to 4-4.