General Information:
Chemical Formula:
(Cu,Ag)21As10
Composition:
(Molecular Weight = 2,172.33 gm)
Copper 55.58 % Cu
Silver 9.93 % Ag
Arsenic 34.49 % As
Empirical Formula:
Cu19Ag2As10
IMA Status:
Approved IMA 1959
Locality:
Cerny Dul mine, near Berghaus, Czech Republic.
Name Origin:
Named for Jiri Novak (1902-1971), Czech mineralogist.
Physical Properties:
Cleavage:
None
Color:
steel gray or black.
Density:
6.7
Diaphaniety:
Opaque
Habits:
Aggregates - Made of numerous individual crystals or clusters., Tarnishes - Freshly fractured surfaces form a surface oxidation film,
Hardness:
3-3.5 - Calcite-Copper Penny
Luster:
Metallic
Streak:
black
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