General Information:
Chemical Formula:
CaZn2(AsO4)2·(H2O)
Composition:
(Molecular Weight = 466.71 gm)
Calcium 8.59 % Ca
Zinc 28.02 % Zn
Arsenic 32.11 % As
Hydrogen 0.43 % H
Oxygen 30.85 % O
Empirical Formula:
CaZn2(AsO4)2·(H2O)
Environment:
Secondary mineral in vugs in partly altered sufide ore.
IMA Status:
Approved IMA 1979
Locality:
Tsumeb mine, Tsumeb, Namibia.
Name Origin:
Named for Prosper J. Williams (1910-), South African-Canadian mineral dealer from Toronto, Canada.
Physical Properties:
Cleavage:
None
Color:
colorless or white.
Density:
4.31
Habits:
Radial - Crystals radiate from a center without producing stellar forms (e.g. stibnite), Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline)., Wheat Sheaf - Bundle shape d aggregates resembling wheat sheafs aft
Hardness:
4.5 - Between Fluorite and Apatite
Luminescence:
Non-fluorescent.
Luster:
Vitreous - Silky
Streak:
white
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