Nomenclature
CAS number: 7782-42-5
Plumbago; black lead; mineral carbon.
Description and references
Obtained by mining, especially in Canada and
Ceylon. Monograph: A. R. Ubbelohde, F. A. Lewis, Graphite and Its Crystal Compounds (Oxford,
1960). Review: Holliday et al. in Comprehensive Inorganic Chemistry vol.
1, J. C. Bailar, Jr. et al., Eds. (Pergamon Press,
Oxford, 1973) pp 1250-1294.
Properties
Crystallized carbon with traces of Fe, SiO2, etc. Usually soft, black scales, crystals rare. d 2.09-2.23. Mohs' hardness
= 1.0. Commercial varieties usually withstand temps up to 2820°.
Sol in molten iron.Caution
Potential symptoms of overexposure
are coughing, dyspnea, black sputum, decreased pulmonary function
and lung fibrosis. See NIOSH Pocket
Guide to Chemical Hazards (DHHS/NIOSH 97-140, 1997) p
154.Use
For “lead” pencils, refractory crucibles, stove
polish; as pigment, lubricant, graphite cement; for matches and explosives,
commutator brushes, anodes, arc-lamp carbons, electroplating; polishing
compds, rust and needle-paper; coating for cathode ray tubes; moderator
in nuclear piles.