Scheelite
Current inventory:  3 gems
 

  
Scheelite is named after the Swedish chemist, Karl Wilhelm Scheele (1742-1786) who discovered the existence of tungsten in Scheelite in 1781.

Discovered in 1821; IMA status: Valid (pre-IMA; Grandfathered)

Chemistry

Chemical Formula:

CaWO₄

Calcium Tungstate

Molecular Weight:

287.93 gm

Composition:

Calcium

13.92 %

Ca

19.48 %

CaO

Tungsten

63.85 %

W

80.52 %

WO₃

Oxygen

22.23 %

O

100.00 %

100.00 %

= TOTAL OXIDE

Classification

Mineral Classification:

Sulfates

Strunz 8th Ed. ID:

6/G.01-20

Nickel-Strunz 10th Ed. ID:

7.GA.05

7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
G : Molybdates, Wolframates and Niobates
A : Without additional anions or H₂O

Related to:

Scheelite Group. Powellite-Scheelite Series. Isostructural with Powellite.

Members of Group:

Scheelite Group: Powellite, Raspite, Scheelite, Stolzite, Wulfenite

Varieties:

Cuprian Scheelite, Molybdoscheelite

Synonyms:

Calcioscheelite, Calcium tungstate, Calciumwolframite, Trimonite, Trimontite, Tungstate of Lime, Tungstite (of Delamëtherie), Tunstitite

Crystal Data

Crystallography:

Tetragonal - Dipyramidal

Crystal Habit:

Crystals are typically pseudo-octahedral {011} or {112}, with modifying forms {001}, {013}, {121}, several others, to 32 cm; commonly granular, massive.

Twinning:

{110}, common, penetration and contact twins, composition plane {110} or {001}.

Physical Properties

Cleavage:

Distinct on {101}; interrupted on {112}; indistinct on {001} 

Fracture:

Irregular/Uneven, Sub-Conchoidal

Tenacity:

Brittle

Moh's Hardness:

4.5 - 5.0

Density:

6.10 (g/cm³)

Luminescence:

Bright bluish white cathodoluminescence and fluorescence under SW UV and X-rays. Thermoluminescent.

Radioactivity:

Not Radioactive

Other:

Decomposed by HCl or HNO3, leaving a yellow powder of hydrous tungstic oxide, which is soluble in ammonia. Alters to Tungstite, Hydrotungstite, or Cuprotungstite. Replaced by Wolframite as perfect pseudomorphs. Often replaces Wolframite.

Optical Properties

Color:

Colorless, white, gray, brown, pale yellow, yellow-orange, pale shades of orange, red, green; may be compositionally color zoned.

Transparency:

Transparent to Opaque; transparent in transmitted light

Luster:

Vitreous to Adamantine

Refractive Index:

1.918 - 1.937  Uniaxial ( + ) 

Birefringence:

0.0160 - 0.0170

Dispersion:

Weak to Strong; r > v

Pleochroism:

None

Occurances

Geological Setting:

Typically a component of contact-metamorphic tactite; in high-temperature hydrothermal veins and greisen; less common in granite pegmatites and medium-temperature hydrothermal veins; alluvial.

Common Associations:

Cassiterite, Wolframite, Topaz, Fluorite, Apatite, Tourmaline, Quartz (greisen); Grossular–Andradite, Diopside, Vesuvianite, Tremolite (tactite).

Common Impurities:

Mo, Nb, Ta

Type Locality:

Bispbergs Klack, Säter, Dalarna, Sweden

Year Discovered:

1821

View mineral photos:

Scheelite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Scheelite is a member of the Scheelite Group of minerals that includes Powellite, Scheelite, Stolzite and Wulfenite. Scheelite is an important ore of tungsten which is a strategically important metal. Scheelite crystals are found at many locations around the world including several in the US. Gem quality, facetable material is somewhat rare however. Ultraviolet lamps can be used to search for Scheelite at night because of its typically bright blue fluorescence. Scheelite has a fairly high refractive index (RI) value of about 1.93 which is similar to the RI value of Sphene and slighlty higher than that of Demantoid Garnet. Scheelite is found in colors of pale yellow, orange-yellow, brownish, greenish, violet, reddish and colorless.

Distribution: An important ore of tungsten, with many localities. Some for fine and large crystals include: from Sweden, at the Bispberg iron mine, near S¨ater, Dalarne. In Germany, from Altenberg and Schwarzenberg, Saxony. At C´inovec (Zinnwald) and Horn´i Slavkov (Schlaggenwald), Czech Republic. From Traversella, Piedmont, Italy. At Tenkergin, Chukotka, Siberia, Russia. In the Natas mine, about 80 km south of Windhoek, Namibia. Large crystals from the Tae wha mine, Chungju, North Chungchong Province, South Korea. At Pia Oac, Tonkin, North Vietnam. In China, from near Pingwu, Xuebao Ding Mountains, Sichuan Province, China. A large deposit in the Flat River Valley, Northwest Territories, Canada. In the USA, in Arizona, large crystals from the Cohen mine, Dragoon Mountains, Cochise Co.; commercially mined at the Pine Creek mine, near Bishop, Inyo Co., California. At Mitopilas, Sonora, Mexico. In the Morro Velho gold mine, Nova Lima, Minas Gerais, Brazil.
 

  
Scheelite gems for sale: