The wolframite Mineral Series
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.
Chemical Formula
(Mn,Fe)WO4
Color
Dark red, dark brown, reddish black, dark gray, black
Crystal System
Monoclinic
Properties
Streak
Reddish brown to black |
Hardness
4 - 4.5 |
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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Crystal Habits
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.
Uses
Wolframite is an important ore of tungsten. Good specimens are not common, and are highly desired by mineral collectors.
Noteworthy Localities
See Huebnerite and Ferberite for specific localities.
Distingushing Similar Minerals
Rutile - Harder, crystals are usually thinner.
Goethite - Has a lower specific gravity.
Columbite-Tantalite series - Different crystal form, cleavage less distinguishable.