Vimsite is a rare calcium hydroxide that forms colorless elongated crystals. Associated minerals include uralborite, andradite-grossular and calciborite. It was first described from Krasnoturinsk, Northern Ural Mountains, Russia.
Is this vimsite?
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 vimsite with a known reference. Vimsite sits at Mohs <4, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: colorless.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: elongated crystals.
Often confused with
Vimsite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Vimsite is noticeably harder (Mohs <4 vs. 2.5); streak differs, so Vimsite leaves white, Pharmacosiderite leaves yellowish green; luster reads vitreous on Vimsite and adamantine to greasy on Pharmacosiderite.
How to tell apart: Vimsite is noticeably harder (Mohs <4 vs. 1.5-2); luster reads vitreous on Vimsite and subvitreous, pearly on {010} cleavages, silky if fibrous on Gypsum.
Often found alongside vimsite
Minerals reported to co-occur with vimsite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaB₂O₂(OH)₄
- Mohs hardness
- <4
- Density
- 2.54 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Elongated crystals
- Cleavage
- Perfect along elongation
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In boron-rich copper-bearing skarn (Novofrolovskoye deposit, Russia); in iron-bearing skarn (Solongo deposit, Russia)
Where rockhounds find vimsite
Classic worldwide localities
- Novofrolovskoye copper deposit, Turinsk district, near Krasnoturinsk, Northern Ural Mountains, and in the Solongo boron deposit, Buryatia, Russia
Field-hunting tip
Where it forms: In boron-rich copper-bearing skarn (Novofrolovskoye deposit, Russia); in iron-bearing skarn (Solongo deposit, Russia). If you start seeing uralborite, andradite–grossular, calciborite in float, you are in the right ground. Typical habit: elongated crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify vimsite?+
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What rocks look like vimsite?+
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Find vimsite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
