Thoreaulite is a very dense and rare tin tantalum oxide mineral primarily found in granitic pegmatites. Collectors often identify it by its high specific gravity, resinous luster, and characteristic tabular crystal habit often associated with other tin and tantalum-bearing minerals.
Is this thoreaulite?
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 thoreaulite with a known reference. Thoreaulite sits at Mohs 5.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Thoreaulite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Thoreaulite typically shows a resinous luster.
- 4Match the color rangeCompare against the expected color range: yellow, brown, colorless, white.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: tabular crystals, massive.
Often confused with
Thoreaulite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside thoreaulite
Minerals reported to co-occur with thoreaulite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- SnTa₂O₆
- Mohs hardness
- 5.5
- Density
- 8.1-8.2 g/cm³
- Streak
- White
- Luster
- Resinous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Tabular Crystals, Massive
- Cleavage
- Distinct On {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Granite Pegmatites
- Typical price
- $100-500 thumbnail, $500+ cabinet
Where rockhounds find thoreaulite
Classic worldwide localities
- Democratic Republic of the Congo
- Brazil
- Canada
Field-hunting tip
Look in granite pegmatites country — that is the host setting where thoreaulite typically forms. If you start seeing cassiterite, microlite, columbite in float, you are in the right ground. Field specimens usually show a tabular crystals, massive habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find thoreaulite on the map
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