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 1.5, 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: submetallic.
- 4Match the color rangeCompare against the expected color range: coal black.
- 5Look at form & habitCrystal system: trigonal. Typical habit: granular, inclusions.
Often confused with
Cronusite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Daubréelite is the harder of the two (Mohs 5 vs. 1.5); streak differs, so Cronusite leaves black, Daubréelite leaves brown; luster reads submetallic on Cronusite and metallic, brilliant on Daubréelite.
How to tell apart: Chromite is the harder of the two (Mohs 5.5 vs. 1.5); streak differs, so Cronusite leaves black, Chromite leaves brown; luster reads submetallic on Cronusite and metallic to 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
- Ca₀.₂CrS₂·2H₂O
- Mohs hardness
- 1.5
- Density
- 2.51 g/cm³
- Colors
- Coal black
- Streak
- Black
- Luster
- Submetallic
- Transparency
- Opaque
- Crystal system
- Trigonal
- Crystal habit
- Granular, inclusions
- Cleavage
- Perfect on {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In an enstatite achondrite meteorite, formed by terrestrial weathering of caswellsilverite
Where rockhounds find cronusite
Classic worldwide localities
- Norton County enstatite achondrite meteorite, Kansas, USA (type locality)
Field-hunting tip
Where it forms: In an enstatite achondrite meteorite, formed by terrestrial weathering of caswellsilverite. If you start seeing enstatite, ferroan alabandite, troilite in float, you are in the right ground. Typical habit: granular, inclusions. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify cronusite?+
Where is cronusite found?+
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Find cronusite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
