Litharge: Properties and Occurrences

Litharge is one of the natural mineral forms of lead (II) oxide, PbO. It is also called Lead Monoxide, Lead Oxide, Plumbous Oxide & Yellow Oxide. Litharge is a secondary mineral which forms from the oxidation of galena ores. It is a yellowish or reddish, odorless, heavy, earthy, water-insoluble, poisonous solid, PbO.

It forms as coatings and encrustations with an internal tetragonal crystal structure. It is dimorphous with the orthorhombic form massicot. This is often done with a set of bellows pumping air over the molten lead and causing the oxidized product to slip or fall off the top into a receptacle, where it quickly solidifies in minute scales.

PbO₂ – (293°C) → Pb₁₂O₁₉ – (351°C) → Pb₁₂O₁₇ – (375°C)→ Pb₃O₄ – (605°C) → PbO.

General Information

Category: Oxide minerals
Formula: PbO
Crystal system: Tetragonal
Crystal class: Ditetragonal dipyramidal (4/mmm)
Color: Red.

Properties

It forms soft (Mohs hardness of 2), red, greasy-appearing crusts with a very high specific gravity of 9.14–9.35. PbO may be prepared by heating lead metal in the air at approximately 600 °C (lead melts at only 300 °C). At this temperature, it is also the end product of oxidation of other lead oxides in the air.

Cleavage: Distinct/Good. On {110}
Mohs scale hardness: 2
Luster: Greasy, dull
Diaphaneity: Transparent
Specific Gravity: 9.5 to 9.9
Thermal Stability: 250° C to 897°C
Density: 9.14 g/cm³ (Measured) and 9.35 g/cm³ (Calculated)
Luminescence: Non-fluorescent.

Occurrences:

Litharge is made by oxidation of lead, wielding a finely divided powder of high purity. It is found with the other form, massicot, as dull or greasy, very heavy, soft, red crusts in the oxidized zone of lead deposits, as at Cucamonga Peak and Fort Tejon, Calif., U.S., and near Hailey, Idaho, U.S.

Chemical Uses: It used chiefly in the manufacture of storage batteries, pottery, lead glass, paints, enamels, and inks.