The tungsten mineral wolframite was known in the tin mines of the Saxony-Bohemia region long before the element itself was discovered. The origin of the word is assumed to be derived from the German words "wolf, meaning beast of prey, and "rham", meaning froth. "It eats up tin as a wolf eats up sheep". The writers of the period before 1781 had vague ideas as to the composition of the mineral that they had named. Tin miners called the mineral "mock-lead", an ore containing iron, arsenic, tin and a nonmetallic earth, or glassy earth containing iron and tin.