Hydrotungstite is a rare secondary tungsten mineral that typically forms as a result of the alteration of scheelite or other tungsten minerals. It is most commonly identified by its soft, yellow-to-green platy crystals that resemble mica, often found as crusts in weathered hydrothermal veins.
Is this hydrotungstite?
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 hydrotungstite with a known reference. Hydrotungstite sits at Mohs 2, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: greenish yellow.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous to dull.
- 4Match the color rangeCompare against the expected color range: yellow green, dark green.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: platy or micaceous aggregates, crusts.
Often confused with
Hydrotungstite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside hydrotungstite
Minerals reported to co-occur with hydrotungstite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- WO₃·2H₂O
- Mohs hardness
- 2
- Density
- 4.60 g/cm³
- Colors
- Streak
- Greenish yellow
- Luster
- Vitreous to dull
- Transparency
- Semitransparent
- Crystal system
- Monoclinic
- Crystal habit
- Platy or micaceous aggregates, crusts
- Cleavage
- {010}, imperfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- An alteration product of ferberite in the oxidized zone of a hydrothermal tungsten deposit, where it was an ore mineral (Calacalani mine, Bolivia)
Where rockhounds find hydrotungstite
Classic worldwide localities
- Oruro district, at the San Antonio de Calacalani mine, near Colquiri, and in the Juliani mine, Bolivia
- Panasqueira, Portugal
- Grancarica scheelite deposit, southwest of Velingrad, Bulgaria
Field-hunting tip
Where it forms: An alteration product of ferberite in the oxidized zone of a hydrothermal tungsten deposit, where it was an ore mineral (Calacalani mine, Bolivia). If you start seeing ferberite, tungstite in float, you are in the right ground. Typical habit: platy or micaceous aggregates, crusts. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify hydrotungstite?+
Where is hydrotungstite found?+
What rocks look like hydrotungstite?+
What minerals are found with hydrotungstite?+
What kind of rock does hydrotungstite form in?+
What is hydrotungstite used for?+
Find hydrotungstite on the map
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