Lithomarge, an earthy or clay-like mineral substance, sometimes called Mountain Marrow
(Ger. Steinmark), consisting chiefly of silica and alumina, with oxide of iron and various colouring substances, derived from the decomposition of various minerals. It is soft, greasy to the touch, and adheres strongly to the tongue. It is generally white, yellow, or red, often exhibiting very beautiful colours. It is found in Germany, Russia, &c., also in the tin-mines of Redruth in Cornwall.