Powellite is a molybdenum-bearing member of the scheelite group, most easily recognized by its vibrant yellow fluorescence under short-wave ultraviolet light. Collectors look for its characteristic tetragonal bipyramidal crystals, which are typically found as pseudomorphs after molybdenite or as vug linings in basaltic rocks.
Is this powellite?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch powellite with a known reference. Powellite sits at Mohs 3.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Powellite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Powellite typically shows a adamantine luster.
- 4Match the color rangeCompare against the expected color range: yellow, brown, greenish-yellow, white, gray.
- 5Look at form & habitCrystal system: tetragonal. Typical habit: bipyramidal crystals, granular, massive.
Often confused with
Powellite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside powellite
Minerals reported to co-occur with powellite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaMoO₄
- Mohs hardness
- 3.5
- Density
- 4.2-4.5 g/cm³
- Streak
- White
- Luster
- Adamantine
- Transparency
- Translucent
- Crystal system
- Tetragonal
- Crystal habit
- Bipyramidal Crystals, Granular, Massive
- Cleavage
- Distinct On {101}
- Fluorescence
- Bright Yellow Under SW UV
- Rarity
- Uncommon
- Uses
- Collector, Indicator Mineral
- Host rock
- Oxidized Zones of Molybdenum-bearing Hydrothermal Deposits and Basalt Cavities
- Typical price
- $20-150 thumbnail, $200-800 cabinet
Where rockhounds find powellite
Classic worldwide localities
- Needles, California, USA
- Krushev Dol, Bulgaria
- Moctezuma, Sonora, Mexico
- Maharashtra, India
Field-hunting tip
Look in oxidized zones of molybdenum-bearing hydrothermal deposits and basalt cavities country — that is the host setting where powellite typically forms. If you start seeing molybdenite, calcite, apophyllite in float, you are in the right ground. Field specimens usually show a bipyramidal crystals, granular, massive habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find powellite on the map
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