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Lead Plumbate

Author: Hans Lohninger

Lead plumbate, also called red lead, minium or Mennige (in German), is a mineral showing colors from light red to brown/yellow tints. As a pure chemical it shows a vivid red. 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 most often associated with galena, cerussite, massicot, litharge, native lead, wulfenite and mimetite.

Minium is obtained by heating lead monoxide (PbO) to 450-480°C in air:

3 PbO + 1/2 O2 Pb3O4

or by oxidative annealing of lead white:

3 Pb2CO3(OH)2 + O2 2 Pb3O4 + 3 CO2 + 3 H2O

Minium decomposes into lead monoxide and oxygen above 550°C.

Pb3O4 can be seen formally as a lead(II)plumbate(IV), Pb2[PbO4], or 2PbOPbO2. In nitric acid the lead(II) oxide reacts forming lead nitrate, while the insoluble lead(IV) oxide is left unchanged:

Pb3O4 + 4 HNO3 2 Pb(NO3)2 + PbO2 + 2 H2O

Minium is virtually insoluble in water. However, it dissolves in hydrochloric acid (which is present in the stomach), and is therefore toxic when ingested. Minium (in a mixture with linseed oil or other organic adhesives) has been used as an anti-corrosion paint for iron. It forms insoluble iron(II) and iron(III) plumbates when brought into contact with iron oxides and with elementary iron. However, its use as a protective undercoat paint is limited due to its toxicity.

Minium was used as a red pigment in ancient and medieval periods for paintings and the production of illuminated manuscripts (the term miniature is connected to the name of the substance).


Home Inorganic Compounds Lead Lead Plumbate

Last Update: 2011-02-16