Litharge (from Greek lithargyros, lithos 'stone' + argyros 'silver' λιθάργυρος) is one of the natural mineral forms of lead(II) oxide, PbO.

It forms soft (Mohs hardness of 2), red, greasy-appearing crusts with a very high specific gravity of 9.14–9.35.

[5] 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.

[7] According to Probert, "silver ore, litharge (crude lead oxide) flux and charcoal were mixed and smelted in very small clay and stone furnaces.

Resulting silver-bearing lead bullion was later refined in a second furnace which yielded fine silver, and litharge skimmings which were used again.