Scheelite
Scheelite is CaWO4, calcium tungstate and an ore of tungsten: tetragonal, hardness 4.5 to 5, density 6.10, white streak, bright bluish white under shortwave UV.
Scheelite is calcium tungstate, Ca(WO4) on the September 2026 IMA list, and the Handbook of Mineralogy calls it an important ore of tungsten. It is tetragonal, hardness 4.5 to 5, density 6.10, with a white streak and bright bluish white fluorescence under shortwave UV. A 20.00 g piece weighs 16.72 g in water, against 12.45 g for quartz.
In short
- The row and the sheet agree. The September 2026 IMA-CNMNC Master List lists scheelite as Ca(WO4), status G, year 1821, country Sweden. The Handbook of Mineralogy scheelite sheet writes CaWO4, the same formula, and says it forms a series with powellite, the molybdenum analogue.
- The tungsten ledger. Worked on standard atomic weights, ideal CaWO4 is 63.85% tungsten by mass, 80.52% as WO3, which is the ideal the sheet prints. Its one analysis, from Schwarzenberg, Saxony, reads WO3 80.17: 63.57% tungsten, with MoO3 0.07. The sheet calls scheelite an important ore of tungsten, with many localities.
- The 16.7-gram check. A 20.00 g piece reads 16.72 g in water at the sheet’s 6.10. Quartz reads 12.45 g, calcite 12.62 g, fluorite 13.70 to 13.72 g, baryte 15.56 g and powellite 15.31 g, all more than 1.1 g lighter. wulfenite (16.92 to 17.33 g) and cassiterite (17.13 to 17.15 g) sit just above it, so the check removes the light pale minerals, not the heavy ones.
- Shortwave, on the sheet. The fluorescence line names SW UV and X-rays and no longwave response. How the glow shifts from blue to yellow as molybdenum rises, and what the gem society records under longwave, is on is scheelite fluorescent.
- Wolframite is not a species row. A script finds no wolframite row on the IMA list; the iron and manganese tungstates are listed as ferberite, Fe2+(WO4), and hübnerite, Mn(WO4). The scheelite sheet names wolframite among its greisen associates, with cassiterite, topaz, fluorite, apatite, tourmaline and quartz.
| Species | IMA formula | Hardness | Density | 20.00 g piece in water | Streak | UV on the sheet |
|---|---|---|---|---|---|---|
| Scheelite | Ca(WO4) | 4.5–5 | 6.10 | 16.72 g | White | Bright bluish white, SW UV and X-rays |
| Powellite | Ca(MoO4) | 3.5–4 | 4.26 | 15.31 g | Not printed | Creamy white or yellow to golden yellow, SW UV |
| Baryte | Ba(SO4) | 3–3.5 | 4.50 | 15.56 g | White | May fluoresce cream to spectral colours, band not named |
| Fluorite | CaF2 | 4 | 3.175–3.184 | 13.70–13.72 g | White | Blue, violet, green, yellow, red, band not named |
| Calcite | Ca(CO3) | 3 | 2.7102 | 12.62 g | White | May fluoresce red, blue, yellow and others, band not named |
| Quartz | SiO2 | 7 | 2.65 | 12.45 g | White | Nothing recorded |
| Wulfenite | Pb(MoO4) | 2.75–3 | 6.5–7.5 | 16.92–17.33 g | White | Nothing recorded |
| Cassiterite | SnO2 | 6–7 | 6.98–7.01 | 17.13–17.15 g | White, pale brown, pale grey | Not read here |
| Hübnerite | Mn(WO4) | 4–4.5 | 7.12–7.18 | 17.19–17.21 g | Yellow to reddish brown, greenish grey | Nothing recorded |
| Ferberite | Fe2+(WO4) | 4–4.5 | 7.58 | 17.36 g | Brownish black to black | Nothing recorded |
| Stolzite | Pb(WO4) | 2.5–3 | 8.34 | 17.60 g | White | May fluoresce red to red-orange LW, lemon-yellow SW |
What is scheelite? The IMA row and the tungsten ledger
The row. The September 2026 IMA-CNMNC Master List lists scheelite as Ca(WO4), status G for grandfathered, year 1821, country Sweden, with a second reference in the Journal of Physics and Chemistry of Solids 46 (1985), 253. The country column records where a mineral was first described; it is not a type-locality field, and the sheet names no type locality.
The tungsten ledger, worked. CaWO4 has a formula mass of 287.91 on standard atomic weights; tungsten, 183.84 of it, is 63.85%. As oxides, the ideal is WO3 80.52 and CaO 19.48, the figures the sheet prints as its ideal composition. The Schwarzenberg analysis reads WO3 80.17, CaO 19.49, MoO3 0.07 and a trace of MgO, which is 63.57% tungsten and 0.047% molybdenum. Scheelite is close to two-thirds tungsten by weight, and that is why it is heavy.
On the sheet. Tetragonal; crystals typically pseudo-octahedral, with several modifying forms, to 32 cm; commonly granular or massive; twinning common, as penetration and contact twins. Cleavage distinct in one direction, interrupted in a second and indistinct in a third. Hardness 4.5 to 5. Transparent to opaque; colourless, white, grey, brown, pale yellow, yellow-orange, pale shades of orange, red or green, and it may be compositionally colour zoned. Streak white; lustre vitreous to adamantine; uniaxial (+), ε = 1.935 to 1.938, ω = 1.918 to 1.921.
How heavy is scheelite? The 16.7-gram check
The 16.7-gram check: a pale, white-streaked 20.00 g piece that weighs 16.6 g or more in water is too heavy for quartz, calcite, fluorite, baryte or powellite, and is in scheelite’s range. Worked as 20 − 20/D from the sheets: scheelite 16.72 g at 6.10; the gem society’s wider 5.9 to 6.3 gives 16.61 to 16.83 g. The nearest of the light group is baryte, 15.56 g, 1.17 g lighter on unrounded figures. The method is on how to measure specific gravity at home.
Where it fails. The check does not separate scheelite from the heavier minerals in the table. Wulfenite starts 0.20 g above it and is a different colour and habit; cassiterite reads 17.13 to 17.15 g and is far harder, 6 to 7. Ferberite and hübnerite, the wolframite end members, read 17.19 to 17.36 g and give dark or coloured streaks where scheelite’s is white. A piece that is part scheelite and part quartz reads between the two, so the check applies to clean material only.
Hardness as the second number. Scheelite at 4.5 to 5 is harder than calcite (3), baryte (3 to 3.5) and fluorite (4), and softer than quartz (7) and cassiterite (6 to 7). The method is on how to test mineral hardness properly.
Is scheelite fluorescent? The sheet line
Yes, under shortwave: the sheet reads Bright bluish white cathodoluminescence and fluorescence under SW UV and X-rays. It names no longwave response. Modreski (New Mexico Geology, 1987) wrote that nearly all scheelite is fluorescent, from luminescence intrinsic to the tungstate ion, and that the colour runs from blue for pure tungsten scheelite to yellow as molybdenum increases.
Across the family. Read ligature-aware, with hemimorphite and willemite as positive controls, three of six tungstate and molybdate sheets record fluorescence: scheelite, powellite and stolzite. Wulfenite, ferberite and hübnerite record none. The molybdenum ladder, the longwave question and lamp choice are on is scheelite fluorescent; why minerals glow at all is on fluorescent minerals explained.
Scheelite and powellite: one series, two species
The series. The scheelite sheet says it forms a series with powellite, and the powellite sheet says the same in reverse. Both are listed by the IMA as separate species: Ca(WO4) and Ca(MoO4). The International Gem Society scheelite article places scheelite in a scheelite group with powellite, stolzite and wulfenite; the IMA list prints no group column, so this page counts no members.
Told apart on the sheets. Powellite is softer, 3.5 to 4 against 4.5 to 5, and much lighter, 4.26 against 6.10: a 20.00 g piece reads 15.31 g in water against 16.72 g, about 1.4 g apart. Powellite is described as an uncommon secondary mineral of the oxidation zone of molybdenum-bearing deposits; scheelite as a component of contact-metamorphic tactite, of high-temperature veins and greisen. The Pine Creek tungsten mine near Bishop, California, is named on both Distribution fields.
Where scheelite is found
Setting. Typically a component of contact-metamorphic tactite; in high-temperature hydrothermal veins and greisen; less common in granite pegmatites and medium-temperature hydrothermal veins; alluvial. Associates in tactite are grossular–andradite, diopside, vesuvianite and tremolite.
Localities the sheet names for fine and large crystals. The Bispberg iron mine near Säter, Dalarne, Sweden; Altenberg and Schwarzenberg, Saxony; Cínovec (Zinnwald) and Horní Slavkov (Schlaggenwald), Czech Republic; Traversella, Piedmont; Tenkergin, Chukotka; the Natas mine south of Windhoek, Namibia; large crystals from the Tae wha mine, Chungju, South Korea; Pia Oac, Vietnam; near Pingwu, Xuebao Ding Mountains, Sichuan; a large deposit in the Flat River Valley, Northwest Territories; the Cohen mine, Dragoon Mountains, Arizona; the Pine Creek mine, California, commercially mined; Mitopilas, Sonora; and the Morro Velho gold mine, Minas Gerais.
On this site. The species pages are listed in the species index, including willemite, the other classic shortwave fluorescer. We hold no catalogue and nothing here is offered for sale; the wanted list is the only commercial route.