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, so Trogtalite leaves black, Pyrite leaves greenish-black to brownish-black.
How to tell apart: Streak differs, so 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, so 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, 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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