Scheelite: Gemstones Information

Scheelite is CaWO4 and forms characteristic colourless to yellow transparent to translucent pseudooctahedral crystals in the tetragonal system with twinning common, hardness 4.5–5, SG 5.9–6.03. The lustre may approach adamantine. The RI for the extraordinary and ordinary rays is 1.935–1.938 and 1.918–1.921, uniaxial positive with birefringence 0.016 and dispersion 0.038. Scheelite shows a conspicuous blue-white fluorescence under SWUV and faint RE lines may be seen in the yellow and green sections of the absorption spectrum.Scheelite occurs in contact metamorphic deposits, hydrothermal veins or pegmatites. Fine-quality transparent crystals are found at Mitopilas, Sonora,Mexico (orange specimens), large crystals from the Bisperg iron mine near Sater, Dalarne, Sweden. There are locations in California and Arizona, USA.Large crystals from the Tae Wha mine, Chungju, North Chungchong Province, South Korea, may not be facetable but are collectable. Both chatoyant and four-rayed star scheelite are known. Scheelite has been made synthetically.