Minium (mineral)

Minium (mineral)
Minium

Minium druse on cerussite from the Old Yuma Mine, Tucson Mountains, Arizona
General
Category Oxide mineral
Chemical formula Pb2+2Pb4+O4
Strunz classification 04.BD.05
Dana classification 07.02.08.01
Crystal symmetry Tetragonal (4/m 2/m 2/m) ditetragonal dipyramidal
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
Crystal system Tetragonal
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 [1][2][3]
Minium produced in the mine fire at Broken Hill

Minium is the naturally occurring form of lead tetroxide, Pb2+2Pb4+O4. It is a light to vivid red and may have brown to yellow tints. It typically occurs as scaly to earthy masses. It crystallizes in the tetragonal crystal system.[1]

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 occurs associated with galena, cerussite, massicot, litharge, native lead, wulfenite and mimetite.[1]

It occurs in a variety of worldwide areas in relatively small amounts. It occurs at Langhecke, Hesse; Badenweiler, Baden-Wurttemberg; Bleialf, Eifel district; Horhausen, 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 USA it is reported from the Jay Gould mine, Alturas County, Idaho; the Leadville district, Lake County, Colorado; in the Tonopah-Belmont mine, Maricopa County, Arizona. It also occurs in Eschuchapa and Guerrero, Mexico.[1] Good specimens were produced by a mine fire at the Broken Hill mine in New South Wales, Australia.[4]

It was named for the Minius River in northwest Spain. The name was originally applied to cinnabar, but after the material was determined to be a coating on the cinnabar, the name minium was applied to the red lead contaminant.[2]

References