Scheelite Identification Guide

What Scheelite Looks Like

Scheelite is calcium tungstate (CaWO4), an important tungsten ore and a prized collector and gem mineral. It ranges from colorless and white to yellow, orange, brown, and gray, and is transparent to translucent with a high vitreous to adamantine (near-diamond) luster that makes it sparkle. Crystals are typically pseudo-octahedral (dipyramidal, looking like double pyramids or octahedra), often with growth striations, and it also forms granular and massive aggregates. Its single most useful field property is its brilliant bluish-white fluorescence under shortwave ultraviolet light — a glow that is almost diagnostic.

Step-by-Step Field Checklist

1. Use a UV lamp. Under shortwave UV, scheelite glows a vivid bright blue to bluish-white; a yellowish glow can indicate molybdenum substitution. This is the best field test.
2. Feel the weight. With a specific gravity around 5.9–6.1 it feels surprisingly heavy for its size.
3. Check luster. Look for a bright adamantine to greasy-vitreous shine.
4. Examine crystal form. Pseudo-octahedral bipyramids with possible striations.
5. Test hardness. Scheelite is fairly soft for its luster, Mohs 4.5–5; a knife scratches it and it will not scratch glass.
6. Look for cleavage. Distinct octahedral (pyramidal) cleavage and brittle fracture.

Key Diagnostic Tests

• Fluorescence: intense blue-white under shortwave UV — near-diagnostic.
• Specific gravity: ~5.9–6.1, very heavy.
• Hardness: 4.5–5; scratched by a knife.
• Luster: vitreous to adamantine.
• Cleavage: distinct pyramidal {101} cleavage; brittle.
• Streak: white.

Common Look-Alikes and How to Tell Them Apart

• Quartz: much harder (Mohs 7), far less dense, and does not fluoresce blue-white under shortwave UV.
• Powellite (CaMoO4): the molybdenum analogue; fluoresces yellow to cream rather than blue-white, and is rarer.
• Cassiterite: dense and adamantine too, but harder (6–7) and gives a pale streak; it does not fluoresce.
• Fluorite: similar hardness (4) but much lower density, cubic/octahedral cleavage in a different geometry, and typically fluoresces blue/violet differently; fluorite forms cubes.
• Topaz/calcite: topaz is harder and lighter; calcite is much softer (3) and fizzes in acid, while scheelite does not react.

Where Scheelite Is Found

Scheelite forms in contact metamorphic skarns, high-temperature hydrothermal veins, and greisens associated with granite intrusions, often with cassiterite, wolframite, molybdenite, and garnet. Notable localities include the European Alps (fine crystals in Austria and Switzerland), China (a major tungsten producer), South Korea, Bolivia, and the western United States (California, Nevada, Arizona). Prospectors famously hunt for it at night with UV lamps because of its glow.