Scheelite

CaWO4
c 2001-2005 Mineral Data Publishing, version 1

Crystal Data: Tetragonal. Point Group: 4/m. 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: On {101}, distinct; on {112}, interrupted; on {001},indistinct. Hardness = 4.5–5 D(meas.) = 6.10(2) D(calc.) = 6.09 Bright bluish whitecathodoluminescence and fluorescence under SW UV and X-rays.
Optical Properties: Transparent to opaque; transparent in transmitted light. Color: Colorless,white, gray, brown, pale yellow, yellow-orange, pale shades of orange, red, green; may becompositionally color zoned. Streak: White. Luster: Vitreous to adamantine.
Optical Class: Uniaxial (+).  = 1.935–1.938 ω = 1.918–1.921
Cell Data:

Space Group: I41 /a (synthetic).

a = 5.2429(3)c = 11.3737(6)Z=4X-ray Powder Pattern: Kernville, California, USA.
3.10 (100), 4.76 (55), 3.072 (30), 1.928 (30), 1.592 (30), 2.622 (25), 2.296 (20)
Chemistry:
WO3
MoO3MgO
CaO

(1)
80.17
0.07
trace
19.49

Total
99.73
(1) Schwarzenberg, Germany. (2) CaWO4 .
Polymorphism & Series:

(2)
80.52

19.48
100.00Forms a series with powellite.

Occurrence: Typically a component of contact-metamorphic tactite; in high-temperaturehydrothermal veins and greisen; less common in granite pegmatites and medium-temperaturehydrothermal veins; alluvial.
Association: Cassiterite, wolframite, topaz, fluorite, apatite, tourmaline, quartz (greisen);grossular–andradite, diopside, vesuvianite, tremolite (tactite).
Distribution: An important ore of tungsten, with many localities. Some for fine and large
crystals include: from Sweden, at the Bispberg iron mine, near Säter, Dalarne. In Germany,from Altenberg and Schwarzenberg, Saxony. At Cı́novec (Zinnwald) and Hornı́ 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, inArizona, large crystals from the Cohen mine, Dragoon Mountains, Cochise Co.; commerciallymined 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.
Name: Honors Karl Wilhelm Scheele (1742–1786), who determined the mineral containedtungsten.
References: (1) Palache, C., H. Berman, and C. Frondel (1951) Dana’s system of mineralogy,(7th edition), v. II, 1075–1077. (2) Hazen, R.M., L.W. Finger, and J.W.E. Mariathasan (1985)
High-pressure crystal chemistry of scheelite-type tungstates and molybdates. J. Phys. Chem.
Solids, 46, 253–263. (3) (1956) NBS Circ. 539, 6, 23.
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