Vauquelinite

Vauquelinite is a complex mineral with the formula CuPb2CrO4PO4OH making it a combined chromate and phosphate of copper and lead. Discovered in 1818 in the Urals it is named after Louis Vauquelin (1763-1829), a French chemist.
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(n.)
Chromate of copper and lead, of various shades of green.
  

General Information:
 Chemical Formula:
Pb2Cu(CrO4)(PO4)(OH)
 Composition:
(Molecular Weight = 705.92 gm)
Chromium 7.37 % Cr
Copper 9.00 % Cu
Phosphorus 4.39 % P 
Hydrogen 0.14 % H 
Lead 58.70 % Pb
Oxygen 20.40 % O 
 Empirical Formula:
Pb2Cu(CrO4)(PO4)(OH)
Physical Properties:
 Cleavage:
[???] Indistinct
 Color:
brown, brownish green, brownish black, green, or black.
 Density:
6
 Diaphaniety:
Transparent to Translucent
 Habits:
Reniform - "Kidney like" in shape (e.g.. hematite)., Mammillary - Larger "breast-like" rounded forms resembling botryoidal (e.g. malachite).,
 Hardness:
2.5-3 - Finger Nail-Calcite
 Luminescence:
Non-fluorescent.
 Luster:
Adamantine - Resinous
 Streak:
brownish
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