4-470: 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 yellow orthorhombic form massicot . It forms soft ( Mohs hardness of 2), red, greasy-appearing crusts with
8-400: A synonym for white lead or red lead. 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." This article about a specific oxide mineral
12-459: A very high specific gravity of 9.14–9.35. PbO may be prepared by heating lead metal in 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 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. Historically,
16-440: 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 ; and 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
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