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, so Kermesite leaves brownish-red, Stibnite leaves lead-gray; luster reads adamantine on Kermesite and metallic on Stibnite.
How to tell apart: Streak differs, so 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, 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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Find kermesite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
