Phyllotungstite is a rare secondary tungsten mineral that typically forms as a dehydration product of primary tungsten ores. Collectors primarily find it as thin, yellow platy crystals or micaceous coatings within vugs of hydrothermal veins.
Is this phyllotungstite?
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 phyllotungstite with a known reference. Phyllotungstite 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: pale yellow.
- 3Read the lusterHold the specimen under a strong light. Luster: pearly.
- 4Match the color rangeCompare against the expected color range: yellow.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: encrustations, scaly, tabular.
Often confused with
Phyllotungstite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Ferberite is the harder of the two (Mohs 4-4.5 vs. ~2); streak differs, so Phyllotungstite leaves pale yellow, Ferberite leaves brownish black to black; luster reads pearly on Phyllotungstite and submetallic to metallic adamantine on Ferberite.
How to tell apart: Scheelite is the harder of the two (Mohs 4.5-5 vs. ~2); streak differs, so Phyllotungstite leaves pale yellow, Scheelite leaves white; luster reads pearly on Phyllotungstite and vitreous to adamantine on Scheelite.
Often found alongside phyllotungstite
Minerals reported to co-occur with phyllotungstite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- HCaFe₃(WO₄)₆(H₂O)₁₀
- Mohs hardness
- ~2
- Density
- 5.26 g/cm³
- Colors
- Streak
- Pale yellow
- Luster
- Pearly
- Transparency
- Translucent
- Crystal system
- Orthorhombic
- Crystal habit
- Encrustations, scaly, tabular
- Cleavage
- On {001}, perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A rare secondary mineral in the oxidized zone of a hydrothermal polymetallic barite–fluorite deposit
Where rockhounds find phyllotungstite
Classic worldwide localities
- Clara mine, near Oberwolfach, Black Forest, Germany
Field-hunting tip
Where it forms: A rare secondary mineral in the oxidized zone of a hydrothermal polymetallic barite–fluorite deposit. If you start seeing ferritungstite, scheelite, pyrite in float, you are in the right ground. Typical habit: encrustations, scaly, tabular. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify phyllotungstite?+
Where is phyllotungstite found?+
What rocks look like phyllotungstite?+
What minerals are found with phyllotungstite?+
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Find phyllotungstite on the map
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