THE MINERAL TSUMEBITE

  • Chemistry: Pb2Cu(PO4)(SO4)OH , Lead Copper Phosphate Sulfate Hydroxide
  • Class: Phosphates
  • Uses: only as a mineral specimen.
  • Specimens

Tsumebite forms good, colorful specimens and is a popular collection mineral, although quite rare. It is closely related to its cousin, arsentsumebite. The two minerals are in a series in which the arsenate ion group in arsentsumebite is replaced by a phosphate ion group in tsumebite. The two differ only slightly mostly because the structure is the same in the two minerals. Both are formed in the oxidation zone of lead-copper ore deposits.

Both minerals are unusual in that they have two ion groups instead of the usual one in most minerals. It the case of tsumebite, it has a phosphate ion group and a sulfate ion group. Mineralogists prefer to classify it as a phosphate because the phosphate ion group has a higher negative charge (-3) than the sulfate group (-2).

PHYSICAL CHARACTERISTICS:

  • Color is emerald green and yellow-green.
  • Luster is vitreous.
  • Transparency crystals are transparent to translucent.
  • Crystal System is monoclinic.
  • Crystal Habits include tabular crystals that can form twinned trillings and also as crusts and spherules.
  • Cleavage: None.
  • Fracture: Uneven.
  • Hardness is 3.5
  • Specific Gravity is approximately 6.2 (heavy for translucent minerals)
  • Streak is green.
  • Associated Minerals include azurite, wulfenite, mimetite, cerussite and smithsonite.
  • Notable Occurrences are limited to Tsumeb, Namibia and Morenci, Arizona, USA.
  • Best Field Indicators are crystal habit, locality, associations, density and color.
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Available TSUMEBITE specimens:
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