Sulphotsumoite is a rare bismuth telluride sulfide that typically appears as metallic, silver-gray foliated masses or lamellar grains. It is most frequently found in hydrothermal gold-bearing deposits and is often visually indistinguishable from other members of the tetradymite group without X-ray diffraction analysis.
Is this sulphotsumoite?
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 sulphotsumoite with a known reference. Sulphotsumoite 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. Sulphotsumoite leaves a gray streak.
- 3Read the lusterHold the specimen under a strong light. Sulphotsumoite typically shows a metallic luster.
- 4Match the color rangeCompare against the expected color range: lead-gray, silver-white.
- 5Look at form & habitCrystal system: trigonal. Typical habit: lamellar to foliated masses.
Often confused with
Sulphotsumoite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside sulphotsumoite
Minerals reported to co-occur with sulphotsumoite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Bi₂Te₂S
- Mohs hardness
- 2
- Density
- 7.9-8.1 g/cm³
- Colors
- Streak
- Gray
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Trigonal
- Crystal habit
- Lamellar to Foliated Masses
- Cleavage
- Perfect Basal
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Gold-bearing Quartz Veins
- Typical price
- $50-300 per specimen
Where rockhounds find sulphotsumoite
Classic worldwide localities
- Tsumo mine, Japan
- Dashkesan, Azerbaijan
- Srednogorie zone, Bulgaria
Field-hunting tip
Look in hydrothermal gold-bearing quartz veins country — that is the host setting where sulphotsumoite typically forms. If you start seeing gold, chalcopyrite, pyrite in float, you are in the right ground. Field specimens usually show a lamellar to foliated masses habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify sulphotsumoite?+
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How much is sulphotsumoite worth?+
What rocks look like sulphotsumoite?+
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Find sulphotsumoite on the map
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