Orpiment

Occurs in Pinal County.

Chemical Formula: As₂S₃

Specific Gravity: 3.49-3.51

Luster: Resinous to pearly

Hardness: 1.5-2

Orpiment is an arsenic sulfide mineral that often forms as orange to yellow crystals or crusts. It is used as a pigment and in traditional medicine.

Next Pinal County mineral: Orthoclase