Katiarsite is an extremely rare copper arsenate mineral discovered in the fumaroles of the Tolbachik volcano in Russia. It typically appears as white, acicular crystal aggregates and crusts associated with volcanic exhalations. Due to its very restricted type locality, it is highly prized by advanced mineral collectors of rare species.
Is this katiarsite?
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 katiarsite with a known reference. Katiarsite sits at Mohs 2.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Katiarsite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Katiarsite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: white, colorless.
- 5Look at form & habitCrystal system: triclinic. Typical habit: crusts, aggregates of small acicular crystals.
Often confused with
Katiarsite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Euchroite is the harder of the two (Mohs 3.5-4 vs. 2.5); streak differs — Katiarsite leaves white, Euchroite leaves pale green.
How to tell apart: Lammerite is the harder of the two (Mohs 3.5 vs. 2.5); streak differs — Katiarsite leaves white, Lammerite leaves light green.
Often found alongside katiarsite
Minerals reported to co-occur with katiarsite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- KCu₅O(AsO₄)₃
- Mohs hardness
- 2.5
- Density
- 2.52 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Triclinic
- Crystal habit
- Crusts, Aggregates of Small Acicular Crystals
- Cleavage
- None Observed
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Fumarolic Deposits
- Typical price
- $100-500+ per specimen
Where rockhounds find katiarsite
Classic worldwide localities
- Tolbachik volcano, Kamchatka, Russia
Field-hunting tip
Look in fumarolic deposits country — that is the host setting where katiarsite typically forms. If you start seeing lammerite, tenorite, sylvite in float, you are in the right ground. Field specimens usually show a crusts, aggregates of small acicular crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find katiarsite on the map
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