Which Metal is Present in Litharge? What is the Use of Litharge? What is the difference between Lead Oxide Yellow and Red

PbO 

Litharge (from Greek lithargyros, lithos (stone) + argyros (silver) λιθάργυρος) is one of the natural mineral forms of lead(II) oxide, PbO. Litharge is a secondary mineral which forms from the oxidation of galena ores. It forms as coatings and encrustations with internal tetragonal crystal structure. It is dimorphous with the orthorhombic form massicot. 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 heating of other lead oxides in the air. This is often done with a set of bellows pumping air over molten lead and causing the oxidized product to slip or fall off the top into a receptacle, where it quickly solidifies in minute scales.

Historical terminology

Historically, the term "litharge" has been combined to refer to other similar substances. For example, litharge of gold is litharge mixed with red lead, giving it a red color; litharge of bismuth is a similar result of the oxidation of bismuth; litharge of silver is litharge that comes as a by-product of separating silver from lead, in fact, litharge originally meant the mineral residue from silver refining. The term has also been used as a synonym for white lead or red lead.

More about Lead Oxide Red in Wikipedia

Formula: PbO
Cleavage: Distinct/Good
Form: red tetragonal crystal structure
Mohs scale hardness: 2
Luster: greasy, dull
Diaphaneity: transparent