VS
Name
—
(Cu,Ag)₂₁As₁₀
Formula
—
Mineral Species
Entry type
—
Sulfosalts
Chemical class
—
Tetragonal
Crystal system
—
3–3.5
Mohs hardness
—
8.01
Specific gravity
—
Black
Streak
—
Metallic. Anisotropism: Medium, dark blue-gray and pale brown-ocher. R1 –R2: (400) 43.6–49.0, (420) 45.4–50.5
Luster
—
—
Cleavage
—
C2/m
Space group
—
—
Structural group
—
Nvá · Approved
IMA
—
1959
Named in
—
Steel-gray on fresh surface, tarnishes iridescent and then black
Typical colors
—
Cu · Ag · As
Elements
—