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Wolframite

Wolframite
Wolframite Hunan.jpg
General
Category Tungstate
Formula
(repeating unit)
(Fe,Mn)WO4
Crystal system Monoclinic
Crystal class Prismatic (2/m)
(same H-M symbol)
Space group P2/c
Unit cell a = 4.77 Å, b = 5.73 Å
c = 4.98 Å; β = 90.2°; Z = 2
Identification
Color Grayish to brownish black
Crystal habit Tabular to short prismatic crystals
Cleavage Perfect 010
Fracture Uneven to rough
Mohs scale hardness 4-4.5
Luster Submetallic to resinous
Streak Reddish brown
Diaphaneity Opaque
Specific gravity 7 - 7.5
Pleochroism None
Fusibility 3 - 4 to magnetic globule
Solubility insoluble
References

Wolframite, (Fe,Mn)WO4, is an iron manganese tungstate mineral that is the intermediate between ferberite (Fe2+ rich) and hübnerite (Mn2+ rich). Along with scheelite, the wolframite series are the most important tungsten ore minerals. Wolframite is found in quartz veins and pegmatites associated with granitic intrusives. Associated minerals include cassiterite, scheelite, bismuth, quartz, pyrite, galena, sphalerite, and arsenopyrite.

This mineral was historically found in Europe in Bohemia, Saxony, and Cornwall. China reportedly has the world's largest supply of tungsten ore with about 60%. Other producers are Canada, Portugal, Russia, Australia, Thailand, South Korea, Rwanda, Bolivia, the United States, and the Democratic Republic of the Congo.

The name "wolframite" is derived from German "wolf rahm", the name given to tungsten by Johan Gottschalk Wallerius in 1747. This, in turn, derives from "Lupi spuma", the name Georg Agricola used for the element in 1546, which translates into English as "wolf's froth" or "cream". The etymology is not entirely certain but seems to be a reference to the large amounts of tin consumed by the mineral during its extraction. Wolfram is the basis for the chemical symbol W for tungsten as a chemical element.


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