Kermesite is a striking, rare secondary mineral that forms as a result of the alteration of stibnite. It is most easily identified by its vibrant cherry-red, hair-like or tufted crystal sprays that contrast beautifully with matrix rock.
Is this kermesite?
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 kermesite with a known reference. Kermesite sits at Mohs 1-1.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Kermesite leaves a brownish-red streak.
- 3Read the lusterHold the specimen under a strong light. Kermesite typically shows a adamantine luster.
- 4Match the color rangeCompare against the expected color range: cherry-red, dark red.
- 5Look at form & habitCrystal system: triclinic. Typical habit: acicular or hair-like tufts.
Often confused with
Kermesite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Kermesite leaves brownish-red, Stibnite leaves lead-gray; luster reads adamantine on Kermesite and metallic on Stibnite.
How to tell apart: Streak differs — Kermesite leaves brownish-red, Realgar leaves orange-red; luster reads adamantine on Kermesite and resinous on Realgar.
Often found alongside kermesite
Minerals reported to co-occur with kermesite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Sb₂S₂O
- Mohs hardness
- 1-1.5
- Density
- 4.68 g/cm³
- Colors
- Streak
- Brownish-red
- Luster
- Adamantine
- Transparency
- Translucent
- Crystal system
- Triclinic
- Crystal habit
- Acicular or Hair-like Tufts
- Cleavage
- Perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Oxidized Zones of Antimony Deposits
- Typical price
- $50-500 depending on specimen size and quality
Where rockhounds find kermesite
Classic worldwide localities
- Příbram, Czech Republic
- Braunsdorf, Germany
- Pereta, Italy
- Hunan, China
Field-hunting tip
Look in oxidized zones of antimony deposits country — that is the host setting where kermesite typically forms. If you start seeing stibnite, senarmontite, valentinite in float, you are in the right ground. Field specimens usually show a acicular or hair-like tufts habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify kermesite?+
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How much is kermesite worth?+
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What rocks look like kermesite?+
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Find kermesite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
