Ullmannite

Ullmannite is a nickel antimony sulfide mineral with formula: (NiSbS). Considerable substitution occurs with cobalt and iron in the nickel site along with bismuth and arsenic in the antimony site. A solid solution series exists with the high cobalt willyamite. It is steel-gray to tin white in colour with a metallic luster. It has a Mohs hardness of 5 to 5.5 and a specific gravity of 6.65. It crystallizes in the isometric crystal class and typically exhibits cubic, octahedral, or pyritohedral forms although euhedral crystals are rare. Crystal twinning is common.
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(n.)
A brittle mineral of a steel-gray color and metallic luster, containing antimony, arsenic, sulphur, and nickel.
  

General Information:
 Chemical Formula:
NiSbS
 Composition:
(Molecular Weight = 212.51 gm)
Nickel 27.62 % Ni
Antimony 57.29 % Sb
Sulfur 15.09 % S 
 Empirical Formula:
NiSbS
 Name Origin:
Named after the German chemist and mineralogist, J. Ch. Ullmann (1771-1821).
Physical Properties:
 Cleavage:
[100] Good, [010] Good, [001] Good
 Color:
steel gray, silver white, or tin white.
 Density:
6.65
 Diaphaniety:
Opaque
 Habits:
Massive - Granular - Common texture observed in granite and other igneous rock., Massive - Uniformly indistinguishable crystals forming large masses.,
 Hardness:
5.5 - Knife Blade
 Luster:
Metallic
 Streak:
grayish black
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ullmannite
danh từ (địa chất, địa lý) Unmanit
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ULLMANNITE