Cuprotungstite is a secondary mineral typically found as earthy crusts or granular masses within the oxidation zones of tungsten deposits. It is most often identified by its distinct pistachio-green color and its intimate association with primary scheelite and secondary tungstite.
Is this cuprotungstite?
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 cuprotungstite with a known reference. Cuprotungstite sits at Mohs 4.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Cuprotungstite leaves a pale yellowish-green streak.
- 3Read the lusterHold the specimen under a strong light. Cuprotungstite typically shows a dull luster.
- 4Match the color rangeCompare against the expected color range: green, yellow-green, pistachio-green.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: massive, crusts, earthy aggregates.
Often confused with
Cuprotungstite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Cuprotungstite leaves pale yellowish-green, Scheelite leaves white; luster reads dull on Cuprotungstite and vitreous on Scheelite.
How to tell apart: Cuprotungstite is noticeably harder (Mohs 4.5 vs. 2.5); streak differs — Cuprotungstite leaves pale yellowish-green, Tungstite leaves yellow; luster reads dull on Cuprotungstite and earthy on Tungstite.
How to tell apart: Streak differs — Cuprotungstite leaves pale yellowish-green, Chrysocolla leaves white; luster reads dull on Cuprotungstite and vitreous on Chrysocolla.
Often found alongside cuprotungstite
Minerals reported to co-occur with cuprotungstite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CuWO₄·2H₂O
- Mohs hardness
- 4.5
- Density
- 4.8-4.9 g/cm³
- Streak
- Pale Yellowish-green
- Luster
- Dull
- Transparency
- Opaque
- Crystal system
- Monoclinic
- Crystal habit
- Massive, Crusts, Earthy Aggregates
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Oxidized Zones of Tungsten-bearing Hydrothermal Deposits
- Typical price
- $20-150 for small specimens
Where rockhounds find cuprotungstite
Classic worldwide localities
- Chile
- Nevada, USA
- China
- Portugal
Field-hunting tip
Look in oxidized zones of tungsten-bearing hydrothermal deposits country — that is the host setting where cuprotungstite typically forms. If you start seeing scheelite, tungstite, limonite in float, you are in the right ground. Field specimens usually show a massive, crusts, earthy aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify cuprotungstite?+
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How much is cuprotungstite worth?+
Is cuprotungstite safe to handle?+
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Find cuprotungstite on the map
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