Massicot

Massicot is lead (II) oxide mineral with an orthorhombic lattice structure.

Lead(II) oxide (formula: PbO) can occur in one of two lattice formats, orthorhombic and tetragonal. The tetragonal form is called litharge. PbO can be changed from massicot to litharge (or vice versa) by controlled heating and cooling. At room temperature massicot forms soft (Mohs hardness of 2) yellow to reddish-yellow, earthy, scaley masses which are very dense, with a specific gravity of 9.64. Massicot can be found as a natural mineral, though it is only found in minor quantities. In bygone centuries it was mined. Nowadays massicot arises during industrial processing of lead and lead oxides, especially in the glass industry, which is the biggest user of PbO.