CaWO4

Calcium tungstate, CaWO4, is a chemical compound that also occurs in nature as the mineral scheelite. It is the principal source of tungsten in many ore deposits and is processed to tungsten oxide and, ultimately, tungsten metal for industrial applications.

In nature, scheelite forms in hydrothermal tungsten-bearing veins, pegmatites, and contact metamorphic deposits associated with granitic intrusions. It is commonly found alongside fluorite, quartz, wolframite, and apatite and occurs in many tungsten-rich districts around the world.

CaWO4 crystallizes in the tetragonal system and commonly occurs as colorless to pale yellow to brown crystals, though it can be translucent to transparent and may exhibit a yellowish color. It has a relatively high density and a Mohs hardness of about 4. It forms prismatic crystals and, when in fine grains, may appear massive or granular. It often displays adamantine to resinous luster.

The mineral exhibits strong blue fluorescence under ultraviolet light, a characteristic helpful for identification in hand specimens and ore sorting. As an ore, scheelite is an important source of tungsten and is processed to recover tungsten trioxide, which is used to produce tungsten metal and alloys for cutting tools, wear parts, and various high-strength applications.