This mineral forms as short, prismatic, striated crystals and also as massive, compact, and granular aggregates. The color is bright red to orange-red. The streak is orange-yellow to orange-red. Realgar is transparent to translucent. It has a resinous to greasy luster.
FORMATION Forms in hydrothermal veins and also around hot springs. It can be found with stibnite and orpiment, as well as with minerals of lead, silver, and antimony.
TESTS As with other arsenic minerals, realgar gives off a strong smell of garlic when heated.
Group: SULFIDES
Composition: AsS
Hardness: 1½–2
SG: 3.56
Cleavage: Good
Fracture: Conchoidal
