Scheelite

A transparent mineral with adamantine luster, Scheelite occurs in white, yellow, orange or greenish gray to brown. Scheelite was named in 1821 after Karl Wilhelm Scheele (1742-1786), the Swedish chemist who proved the existence of tungsten in the mineral in 1781.

Composed of Calcium Tungstate (CaWO4), Scheelite is known as an important ore of tungsten. Although most of the world wide production of tungsten comes from the mineral Wolframite, Scheelite is especially abundant in the United States and provides the country with most of its supply.

Scheelite is also a popular mineral for collectors. As well as having an interesting crystal structure, it fluoresces an intense blue color in ultraviolet light. It can sometimes be confused with Fluorite, however Scheelite is actually higher in luster. Massive Scheelite has also often been mistaken for massive Quartz, but then the blue fluorescence of Scheelite is a dead giveaway.

Many prospectors for Scheelite have made good use of Scheelite's typically bright blue fluorescence by searching for Scheelite deposits by night with ultraviolet lamps. Many old mines have even been reopened after examination of the mine shafts with ultraviolet lamps have proven that the ore is not quite yet exhausted.

Notable occurrences of Scheelite include: Ontario, Canada; Saxony, Germany; Tong Wha, Korea; Sichuan, China; Sonora, Mexico; Cornwall, England; New South Wales and Queensland, Australia; and Brazil. In the USA it has been found in California, Arizona, Utah and Colorado.

With a hardness of 4.5 to 5 on the Moh’s Scale, Scheelite is a rather soft stone. Traditionally, it was considered a collector's gem and unsuitable for use in jewelry. However, facet grade Scheelite does occur in several world locations, especially the recently discovered deposit at Pingwu, Sichuan Province in China. These deposits produce specimens with a beautiful yellow to golden orange color that complements its adamantine luster and intense blue fluorescence.