Tetrarooseveltite is a rare bismuth arsenate mineral that occurs as a secondary mineral in oxidized zones of arsenic-rich hydrothermal deposits. It is best identified by its bright yellow color and association with other bismuth-bearing secondary minerals in uranium-rich mining districts.
Is this tetrarooseveltite?
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 tetrarooseveltite with a known reference. Tetrarooseveltite sits at Mohs 2.5, 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: earthy.
- 4Match the color rangeCompare against the expected color range: white, yellowish white.
- 5Look at form & habitCrystal system: tetragonal. Typical habit: aggregates, powdery.
Often confused with
Tetrarooseveltite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Rooseveltite is the harder of the two (Mohs 4-4.5 vs. 2.5); luster reads earthy on Tetrarooseveltite and adamantine on Rooseveltite.
How to tell apart: Atelestite is the harder of the two (Mohs 4.5-5 vs. 2.5); luster reads earthy on Tetrarooseveltite and resinous to adamantine on Atelestite.
Often found alongside tetrarooseveltite
Minerals reported to co-occur with tetrarooseveltite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Bi(AsO₄)
- Mohs hardness
- 2.5
- Density
- 7.64 g/cm³
- Colors
- Streak
- White
- Luster
- Earthy
- Transparency
- Semitransparent
- Crystal system
- Tetragonal
- Crystal habit
- Aggregates, powdery
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A rare secondary mineral in vugs in an oxidized fluorite–barite–quartz vein
Where rockhounds find tetrarooseveltite
Classic worldwide localities
- Moldava fluorite mine, about 20 km northwest of Teplice, Krušné hory Mountains, Czech Republic
Field-hunting tip
Where it forms: A rare secondary mineral in vugs in an oxidized fluorite–barite–quartz vein. If you start seeing bayldonite, malachite, mimetite in float, you are in the right ground. Typical habit: aggregates, powdery. Train your eye for that shape before scanning the outcrop.
Common questions
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Find tetrarooseveltite on the map
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