- Chemistry: Pb2Cu(PO4)(SO4)OH
, Lead Copper Phosphate Sulfate Hydroxide
- Class: Phosphates
- Uses: only as a mineral specimen.
Tsumebite forms good, colorful specimens and is a popular collection
mineral, although quite rare. It is closely related to its cousin,
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).
- 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
- Streak is green.
- Associated Minerals include azurite,
- Notable Occurrences are limited to Tsumeb, Namibia and Morenci,
- Best Field Indicators are crystal habit, locality, associations,
density and color.