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 ~7, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: black.
- 3Read the lusterHold the specimen under a strong light. Luster: metallic.
- 4Match the color rangeCompare against the expected color range: pink violet.
- 5Look at form & habitCrystal system: cubic. Typical habit: irregular grains.
Often confused with
Trogtalite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Trogtalite leaves black, Pyrite leaves greenish black to brownish black.
How to tell apart: Trogtalite is noticeably harder (Mohs ~7 vs. 5.5); streak differs, so Trogtalite leaves black, Cobaltite leaves grayish black.
How to tell apart: Trogtalite is noticeably harder (Mohs ~7 vs. 2.5-3); streak differs, so Trogtalite leaves black, Clausthalite leaves grayish 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
- ~7
- Density
- 7.09 g/cm³
- Colors
- Pink violet
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Cubic
- Crystal habit
- Irregular grains
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Intergrown with clausthalite (Trogtal quarry, Germany)
Where rockhounds find trogtalite
Classic worldwide localities
- Trogtal quarry, near Lautenthal, Harz Mountains, Germany (type locality)
- Musonoi Cu–Co mine, near Kolwezi, Katanga Province, Congo (Shaba Province, Zaire)
- Tuminico, Sierra de Cacho, and at Los Llantenes, La Rioja Province, Argentina
Field-hunting tip
Where it forms: Intergrown with clausthalite (Trogtal quarry, Germany). If you start seeing clausthalite, hastite, bornhardtite in float, you are in the right ground. Typical habit: irregular grains. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify trogtalite?+
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Is trogtalite safe to handle?+
What rocks look like trogtalite?+
What minerals are found with trogtalite?+
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Find trogtalite on the map
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