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The wolframite Mineral Series
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Wolframite is not scientifically classified as an individual
mineral species by the IMA. However, it is universally recognized as a mineral series, with the minerals Huebnerite and Ferberite being its end members. Huebnerite is the manganese-rich end member, and Ferberite is the iron-rich end member. The term Wolframite can be used generally to describe unspecified members of this group, or to describe the intermediary member of this series. Wolframite is named for its tungsten content, since wolfram means tungsten in German.
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Chemical Formula |
(Mn,Fe)WO4 |
Composition |
Manganese iron tungstate
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Color |
Dark red, dark brown, reddish black, dark gray, black |
Streak |
Reddish brown to black |
Hardness |
4 - 4.5 |
Crystal System |
Monoclinic |
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Crystal Forms and Aggregates |
Most often in long prismatic crystals, columnar groups, blocky and chisel-shaped crystals, and flattened tabular crystals. Also in dense bladed clusters and rosettes, reticulated, acicular, grainy, in veins, encrusting, and massive. Crystals are often striated lengthwise, and may be twinned as repeated twins with a v-shaped notch in the center.
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Transparency |
Opaque. May be translucent in thin splinters or when backlit. |
Specific Gravity |
7.1 - 7.5 |
Luster |
Adamantine, submetallic |
Cleavage |
1,1. May exhibit parting between crystals. |
Fracture |
Uneven |
Tenacity |
Brittle |
Other ID Marks |
May be weakly attracted to magnets in iron-rich specimens.
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In Group |
Tungstates and Molybdates; Tungstates |
Striking Features |
Heavy weight, color, cleavage, and mode of occurrence. |
Environment |
Tungsten deposits composed of high and medium temperature hydrothermal Quartz veins; also in granite pegmatites.
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Rock Type |
Igneous, Metamorphic |
Popularity (1-4)
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2 |
Prevalence (1-3)
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3 |
Demand (1-3) |
1 |
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Wolframite is an important ore of tungsten. Good specimens are not common, and are highly desired by mineral collectors.
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See Huebnerite and Ferberite for specific localities.
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Rutile - Harder, crystals are usually thinner. Goethite - Has a lower specific gravity. Columbite-Tantalite series - Different crystal form, cleavage less distinguishable.
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