Scheelite
Scheelite | ||
---|---|---|
Specific gravity 5.9–6.1 | | |
Optical properties | Uniaxial (+) | |
Refractive index | nω = 1.918–1.921, nε = 1.935–1.938 | |
Birefringence | δ = 0.017 | |
Pleochroism | Definite dichoric in yellow (yellow to orange-brown) | |
Fusibility | With difficulty | |
Solubility | Soluble in alkalis. Insoluble in acids | |
Other characteristics | Fluorescence under short-wave UV is bright blue, bluish white to yellow. Specimens with more molybdenum tend to fluoresce white to yellow, similar to powellite. Occasionally fluoresces red under mid-wave UV. | |
References | [2][3][4][5] |
Scheelite is a
Properties
Its crystals are in the
Gems cut from transparent material are fragile. Scheelite's refractive index (1.918–1.937 uniaxial positive, with a maximum birefringence of 0.016) and dispersion (0.026) are both moderately high. These factors combine to result in scheelite's high lustre and perceptible "fire", approaching that of diamond.
Scheelite fluoresces under shortwave ultraviolet light, the mineral glows a bright sky-blue. The presence of molybdenum trace impurities occasionally results in a green glow. Fluorescence of scheelite, sometimes associated with native gold, is used by geologists in the search for gold deposits.
Occurrence
Scheelite occurs in
Scheelite usually occurs in tin-bearing veins; and is sometimes found in association with gold. Fine crystals have been obtained from Caldbeck Fells in
History
Scheelite was first described in 1751 for an occurrence in Mount Bispbergs klack, Säter, Dalarna, Sweden, and named for Carl Wilhelm Scheele (1742–1786).[3] Owing to its unusual heaviness, it had been given the name tungsten by the Swedes, meaning “heavy stone.” The name was later used to describe the metal, while the ore itself was given the name scheelerz or scheelite.[11]
Synthetics
Although it is now[when?] uncommon as a diamond imitation (much more convincing products, like cubic zirconia and moissanite have long since superseded it), synthetic scheelite is occasionally[when?] offered as natural scheelite, and collectors[who?] may thus be fooled[by whom?] into paying high[quantify] prices for them. Gemologists distinguish natural scheelite from synthetic material mainly by microscopic examination: Natural material is very seldom without internal growth features and inclusions (imperfections), while synthetic material is usually very clean. Distinctly artificial curved striae and clouds of minute gas bubbles may also be observed[by whom?] in synthetic scheelite.
The visible
In popular culture
Scheelite figures in the manga series Dr. Stone, as a precursor to tungsten, and for its fluorescence.[12]
References
- S2CID 235729616.
- ^ a b c d http://rruff.geo.arizona.edu/doclib/hom/scheelite.pdf Handbook of Mineralogy
- ^ a b http://www.mindat.org/min-3560.html Mindat.org
- ^ http://webmineral.com/data/Scheelite.shtml Webmineral data
- ISBN 0-471-80580-7.
- .
- ^ Lindgren, W. (1933) Ore Deposits of the Western States, pp. 518, 535
- ^ Chisholm, Hugh, ed. (1911). . Encyclopædia Britannica (11th ed.). Cambridge University Press.
- ^ Amstutz, Gerhard Christian et al. (Ed.). Ore Genesis: The State of the Art. Vol. 2. Springer Science & Business Media, 2012, p. 418.
- ^ "洛阳钼业去年净利增长25%,贡献最大的这两项业务|界面新闻".
- ^ Reynolds, Francis J., ed. (1921). Collier's New Encyclopedia. New York: P. F. Collier & Son Company. .
- ^ Gleeson, Kayla (2019-12-07). "English Dub Review: Dr. STONE "Spartan Crafts Club"". Bubbleblabber. Retrieved 2021-01-26.
Further reading
- Anderson, B. W., Jobbins, E. A. (Ed.) (1990). Gem testing. Butterworth & Co Ltd, Great Britain. ISBN 0-408-02320-1