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Wolframite
Current inventory:  0 gems
 

  
Wolframite's name is derived from the German word volf for wolf, and rahm for froth or cream, perhaps in allusion to an objectionable scum formed during the smelting of tin ores containing tungsten.

Discovered in 1863.   IMA status: Not Valid (Group name)

Chemistry

Chemical Formula:

(Fe²⁺;Mn²⁺)WO₄

Iron Manganese Tungstate

Molecular Weight:

303.24 gm

Composition:

Manganese

9.06 %

Mn

11.70 %

MnO

Iron

9.21 %

Fe

11.85 %

FeO

Tungsten

60.63 %

W

76.46 %

WO₃

Oxygen

21.10 %

O

100.00 %

100.00 %

= TOTAL OXIDE

Classification

Mineral Classification:

Oxides

Strunz 8th Ed. ID:

4/D.16-20

Nickel-Strunz 10th Ed. ID:

4.DB.30

4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
D : Metal: Oxygen = 1:2 and similar
B : With medium-sized cations; chains of edge-sharing octahedra

Related to:

Wolframite Group, Wolframite is chemically intermediate between Hübnerite and Ferberite with unspecified chemical composition.

Synonyms:

Cal, Call, Gal, Mock-lead, Prismatic scheelium ore, Scheelate of Iron and Manganese, Tungstate of Iron and Manganese, Tungstic acid, iron, and manganese

Crystal Data

Crystallography:

Monoclinic - Prismatic

Crystal Habit:

As wedge-shaped crystals, typically flattened {100} and elongated along [010] or, less commonly, along [001], to 15 cm; faces striated k [001] or [010]; in groups of bladed crystals; massive.

Twinning:

Contact twins with composition plane {100} or {023}, or more rarely {001}; also interpenetrant or lamellar.

Physical Properties

Cleavage:

Perfect on {010}, Parting on {100} and {102}

Fracture:

Irregular/Uneven

Tenacity:

Brittle

Moh's Hardness:

4.0 - 4.5

Density:

7.58 (g/cm³)

Luminescence:

None

Radioactivity:

Not Radioactive

Other:

Slightly magnetic. Decomposed by aqua regia with the separation of tungstic oxide. Forms pseudomorphs after Scheelite. Often more or less completely replaced by Scheelite. Pseudomorphs of Quartz, Hematite, Marcasite, and Kaolinite after Wolframite noted.

Optical Properties

Color:

Black; dark Brown in transmitted light

Transparency:

Opaque

Luster:

Submetallic to Metallic Adamantine

Refractive Index:

R1–R2: (400) 16.5–19.5, (420) 16.4–19.2, (440) 16.3–18.9, (460) 16.2–18.7, (480) 15.9–18.5, (500) 16.0–18.7, (520) 16.0–18.7, (540) 16.0–18.7, (560) 16.0–18.7, (580) 15.8–18.6, (600) 15.8–18.6, (620) 15.7–18.6, (640) 15.6–18.5, (660) 15.5–18.3, (680) 15.4–18.1, (700) 15.5–18.0

Birefringence:

0.000 (Opaque)

Anisotrophism:

Distinct; Bireflectance: Weak

Occurances

Geological Setting:

In high-temperature hydrothermal veins, greisens, and granitic pegmatites; also residual in alluvial and eluvial deposits.

Common Associations:

Topaz, Scheelite, Quartz

Year Discovered:

1863

View mineral photos:

Wolframite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Wolframite is chemically intermediate between Hübnerite and Ferberite with unspecified chemical composition. Wolframite is actually a series between these two minerals. Hübnerite is the Manganese rich end member and Ferberite is the iron rich end member. Wolframite is the name of the series and the name applied to indistinguishable specimens and specimens intermediate between the two end members. Only specimens that are more than 80% pure manganese are called Hübnerite and only specimens more than 80% pure iron are called Ferberite.

There are many localities worldwide for Worlframite. Possibly the largest and best specimens are from the Guangdong and Hunan Provinces, China.
 

  
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