realgar
/rɪˈalɡə
/noun [mass noun]
A soft reddish mineral consisting of arsenic sulphide, formerly used as a pigment and in fireworks.Orpiment is a lesser mineral associated with realgar and lead sulfosalts in dolomite at Binnental, Valais, Switzerland....
- It is an alteration product of realgar, native arsenic, and, less commonly, arsenopyrite.
- The next morning we drove west to the famous town of Shimen, the locality for all the superb realgar and orpiment crystals.
Origin
Late Middle English: via medieval Latin from Arabic rahj al-ġār 'arsenic', literally 'dust of the cave'.