Realgar - Natural minerals and crystals

Realgar is a mineral species, composed of arsenic sulphide. The word comes from the Arabic "rhag al-ghar" (cave dust), or from "rhag al-far" (powder of rats) because of a reading error: the realgar was indeed used as mortar. -rats. Realgar is a common mineral in low temperature hydrothermal veins associated with the minerals arsenic and antimony.