Minium is a scarce lead oxide mineral (Pb3O4) that generally forms red, powdery coatings in highly oxidized lead ore deposits. It has a nonmetallic luster, a red color, orangish-yellow streak, several directions of cleavage, is soft (H = 2.5 to 3), and has a high specific gravity (due to the lead content). It typically occurs in massive, earthy, or granular forms. It can also form fine, scale-like crystal masses. Crystal faces and cleavage planes can be striated.
Minium from Lake County, Colorado, USA (CSM # 53269, Colorado School of Mines Geology Museum, Golden, Colorado, USA).
Minium from the Stone Mine, Leadville District, Lake County, Colorado, USA (CSM # 4779, Colorado School of Mines Geology Museum, Golden, Colorado, USA).