Cronusite is a rare chromium sulfide mineral typically discovered as microscopic grains within iron meteorites. It is notable for its occurrence in extraterrestrial environments, appearing as thin plates or massive patches associated with other iron-sulfide phases.
Is this cronusite?
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 cronusite with a known reference. Cronusite sits at Mohs 3.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Cronusite leaves a black streak.
- 3Read the lusterHold the specimen under a strong light. Cronusite typically shows a metallic luster.
- 4Match the color rangeCompare against the expected color range: black.
- 5Look at form & habitCrystal system: trigonal. Typical habit: platy hexagonal crystals and massive aggregates.
Often confused with
Cronusite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Luster reads metallic on Cronusite and submetallic on Daubréelite.
How to tell apart: Chromite is the harder of the two (Mohs 5.5 vs. 3.5); streak differs — Cronusite leaves black, Chromite leaves dark brown; luster reads metallic on Cronusite and submetallic on Chromite.
Often found alongside cronusite
Minerals reported to co-occur with cronusite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- K₀.₂₅CrS₂
- Mohs hardness
- 3.5
- Density
- 4.45 g/cm³
- Colors
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Trigonal
- Crystal habit
- Platy Hexagonal Crystals and Massive Aggregates
- Cleavage
- Perfect Basal
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Meteorites
- Typical price
- expensive
Where rockhounds find cronusite
Classic worldwide localities
- Noroit-1 meteorite, Egypt
Field-hunting tip
Look in meteorites country — that is the host setting where cronusite typically forms. If you start seeing daubréelite, troilite, kamacite in float, you are in the right ground. Field specimens usually show a platy hexagonal crystals and massive aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find cronusite on the map
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