Trogtalite is a rare cobalt selenide mineral typically found as massive or disseminated grains in selenide-rich hydrothermal veins. Collectors usually identify it by its distinct association with other rare selenide species in specialized mineral suites.
Is this trogtalite?
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 trogtalite with a known reference. Trogtalite sits at Mohs 4.5-5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Trogtalite leaves a black streak.
- 3Read the lusterHold the specimen under a strong light. Trogtalite typically shows a metallic luster.
- 4Match the color rangeCompare against the expected color range: gray, dark gray, black.
- 5Look at form & habitCrystal system: cubic. Typical habit: massive, anhedral grains.
Often confused with
Trogtalite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Pyrite is the harder of the two (Mohs 6-6.5 vs. 4.5-5); streak differs — Trogtalite leaves black, Pyrite leaves greenish-black to brownish-black.
How to tell apart: Streak differs — Trogtalite leaves black, Cobaltite leaves greyish-black.
How to tell apart: Trogtalite is noticeably harder (Mohs 4.5-5 vs. 2.5-3); streak differs — Trogtalite leaves black, Clausthalite leaves gray-black.
Often found alongside trogtalite
Minerals reported to co-occur with trogtalite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CoSe₂
- Mohs hardness
- 4.5-5
- Density
- 7.3 g/cm³
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Cubic
- Crystal habit
- Massive, Anhedral Grains
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Veins
- Typical price
- $50-300 per specimen
Where rockhounds find trogtalite
Classic worldwide localities
- Trogtal, Harz Mountains, Germany
- Musonoi mine, Democratic Republic of the Congo
- Kukisvumchorr, Khibiny Massif, Russia
Field-hunting tip
Look in hydrothermal veins country — that is the host setting where trogtalite typically forms. If you start seeing clausthalite, tiemannite, selenide minerals in float, you are in the right ground. Field specimens usually show a massive, anhedral grains habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find trogtalite on the map
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