Minium is the naturally occurring form of lead tetroxide, Pb2+2Pb4+O4 also known as red lead. It is red lead oxide, sometimes found as a mineral but usually prepared synthetically; tri-lead tetroxide. It is a reddish oxide of lead, used as a pigment in paints and in glass and ceramics
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.
General Information
- Category: Oxide mineral
- Formula: (repeating unit) Pb2+2Pb4+O4
- Crystal system: Tetragonal
- Crystal class: Ditetragonal dipyramidal (4/mmm)
- Color: Scarlet to brownish red, may have a yellowish tint.
Fig: Minium – a light-to-vivid red
Properties
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.
- 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
Occurrence – A rare secondary mineral in some highly oxidized lead-bearing mineral deposits; may form during mine fires.
It occurs in relatively small amounts throughout the world: Langhecke, Hesse; Badenweiler, Baden-Württemberg; 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.
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.
Association: Galena, cerussite, massicot, litharge, lead, wulfenite, mimetite.
