Minium (mineral)

Minium
Minium druse on cerussite from the Old Yuma Mine, Tucson Mountains, Arizona
General
Category	Oxide mineral
Formula (repeating unit)	Pb2+2Pb4+O4
Strunz classification	4.BD.05
Dana classification	07.02.08.01
Crystal system	Tetragonal
Crystal class	Ditetragonal dipyramidal (4/mmm) H-M symbol: (4/m 2/m 2/m)
Space group	P42/mbc
Unit cell	a = 8.811(5) Å, c = 6.563(3) Å; Z = 4
Identification
Color	Scarlet to brownish red, may have a yellowish tint
Crystal habit	Scaly; commonly as earthy, pulverulent masses
Cleavage	Perfect on {110} and {010}
Mohs scale hardness	2.5
Luster	Dull to slightly greasy
Streak	Yellow-orange
Diaphaneity	Semitransparent
Specific gravity	8.9 - 9.2
Optical properties	Uniaxial
Refractive index	n = 2.42
References

Minium is the naturally occurring form of lead tetroxide, Pb²⁺₂Pb⁴⁺O₄ also known as red lead. Minium is a light-to-vivid red and may have brown-to-yellow tints. It typically occurs in scaly-to-earthy masses. It crystallizes in the tetragonal crystal system.

Minium is rare and occurs in lead-mineral deposits that have been subjected to severe oxidizing conditions. It also occurs as a result of mine fires. It is associated with cerussite, galena, litharge, massicot, mimetite, native lead, and wulfenite.

It occurs in relatively small amounts throughout the world: Langhecke, Hesse; Badenweiler, Baden-Württemberg; Bleialf, Eifel district; Horhausen (Grube Holzappel ()), Rhineland-Palatinate in Germany. It occurs at Mies, Slovenia; Leadhills, Lanarkshire, Scotland; Castelberg St. Avold, Moselle, France; from Langban, Varmland, Sweden; Sarrabus, Sardinia, Italy; near Anarak, Iran; and Tsumeb, Namibia. In the US, mines include the Jay Gould mine, Alturas County, Idaho; the Leadville district, Lake County, Colorado; and in the Tonopah-Belmont mine, Maricopa County, Arizona. It also occurs in Eschuchapa and Guerrero, Mexico. Good specimens were produced by a mine fire at the Broken Hill mine in New South Wales, Australia.