Nickeltyrrellite is an extremely rare copper-nickel selenide mineral belonging to the thiospinel group. It typically occurs as microscopic grains or massive aggregates in selenium-rich ore deposits, often associated with other rare selenides and uranium minerals.
Is this nickeltyrrellite?
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 nickeltyrrellite with a known reference. Nickeltyrrellite 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. Nickeltyrrellite leaves a dark grey streak.
- 3Read the lusterHold the specimen under a strong light. Nickeltyrrellite typically shows a metallic luster.
- 4Match the color rangeCompare against the expected color range: dark gray, black.
- 5Look at form & habitCrystal system: cubic. Typical habit: granular to massive.
Often confused with
Nickeltyrrellite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Nickeltyrrellite leaves dark grey, Linnaeite leaves black.
How to tell apart: Nickeltyrrellite is noticeably harder (Mohs 4.5-5 vs. 2.5-3); streak differs — Nickeltyrrellite leaves dark grey, Clausthalite leaves gray-black.
How to tell apart: Nickeltyrrellite is noticeably harder (Mohs 4.5-5 vs. 3); streak differs — Nickeltyrrellite leaves dark grey, Bornite leaves greyish black.
Often found alongside nickeltyrrellite
Minerals reported to co-occur with nickeltyrrellite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CuNi₂Se₄
- Mohs hardness
- 4.5-5
- Density
- 5.68 g/cm³
- Streak
- Dark Grey
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Cubic
- Crystal habit
- Granular to Massive
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Selenium-rich Veins
- Typical price
- $50-200 per small specimen
Where rockhounds find nickeltyrrellite
Classic worldwide localities
- Tyrell's Lake, Saskatchewan, Canada
- Tilkerode, Harz Mountains, Germany
Field-hunting tip
Look in hydrothermal selenium-rich veins country — that is the host setting where nickeltyrrellite typically forms. If you start seeing clausthalite, uraninite, selenite in float, you are in the right ground. Field specimens usually show a granular to massive habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find nickeltyrrellite on the map
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