Anthoinite is a rare aluminum tungstate mineral that typically occurs as soft, powdery, or earthy coatings on other tungsten-bearing ores. It is primarily identified by its distinctive pearly luster when found in small, dense aggregates within weathered pegmatite deposits.
Is this anthoinite?
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 anthoinite with a known reference. Anthoinite sits at Mohs 1, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: dull.
- 4Match the color rangeCompare against the expected color range: white.
- 5Look at form & habitCrystal system: triclinic. Typical habit: earthy.
Often confused with
Anthoinite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside anthoinite
Minerals reported to co-occur with anthoinite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- AlWO₃(OH)₃
- Mohs hardness
- 1
- Density
- 4.78-4.87 g/cm³
- Colors
- Streak
- White
- Luster
- Dull
- Transparency
- Translucent
- Crystal system
- Triclinic
- Crystal habit
- Earthy
- Cleavage
- One direction, perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In placers with cassiterite and wolframite and in quartz veins with ferberite, which appears to replace it (Mt. Misobo mine, Congo); in altered skarn (Kara mine, Tasmania)
Where rockhounds find anthoinite
Classic worldwide localities
- Mt. Misobo tungsten mine, Kalima-Maniema district, and the Mierge mine, Kivu Province, Congo (Zaire)
- Bugarama and Gifurwe mines, Rwanda
- Bengo-Biri, Kalima, Congo Republic
- Nyamulilo mine, Kigezi district, and the Bjordal mine, Kabole, Uganda
- Kara mine, southwest of Burnie, Tasmania, Australia
- Flo property, Kalzas Mountain, 67 km southeast of Mayo, Yukon Territory, Canada
Field-hunting tip
Where it forms: In placers with cassiterite and wolframite and in quartz veins with ferberite, which appears to replace it (Mt. Misobo mine, Congo); in altered skarn (Kara mine, Tasmania). If you start seeing ferberite, scheelite, mpororoite in float, you are in the right ground. Typical habit: earthy. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify anthoinite?+
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Find anthoinite on the map
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