Litharge

Litharge
General
CategoryOxide minerals
Formula
(repeating unit)
PbO
IMA symbolLit[1]
Strunz classification4.AC.20
Crystal systemTetragonal
Crystal classDitetragonal dipyramidal (4/mmm)
H-M symbol: (4/m 2/m 2/m)
Space groupP4/nmm
Identification
Colorred
CleavageDistinct/Good. On {110}
Mohs scale hardness2
Lustergreasy, dull
Diaphaneitytransparent
References[2][3][4]

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 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.[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.[6]

PbO2 –(293 °C)→ Pb12O19 –(351 °C)→ Pb12O17 –(375 °C)→ Pb3O4 –(605 °C)→ PbO
  1. ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
  2. ^ Mineralienatlas
  3. ^ Mindat
  4. ^ Webmineral data
  5. ^ N.N. Greenwood, A. Earnshaw, "Chemistry of Elements", 2nd edition, Butterworth-Heinemann, 1997.
  6. ^ "VI. Semivitrified Oxide of Lead - Oxide of Lead. - Plumbi Oxidum. Us. - Litiiargyrum. Br. - Litharge".