Frolovite is a rare calcium borate mineral that typically forms as white, radiating crystal clusters in contact metamorphic zones. Collectors prize it for its unique habit and association with other rare borate minerals in skarn environments.
Is this frolovite?
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 frolovite with a known reference. Frolovite sits at Mohs 3.5, 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 to dull.
- 4Match the color rangeCompare against the expected color range: white, gray white.
- 5Look at form & habitCrystal system: triclinic. Typical habit: irregular grains.
Often confused with
Frolovite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Colemanite is the harder of the two (Mohs 4.5 vs. 3.5).
How to tell apart: Frolovite is noticeably harder (Mohs 3.5 vs. 2).
How to tell apart: Frolovite is noticeably harder (Mohs 3.5 vs. 2.5).
Often found alongside frolovite
Minerals reported to co-occur with frolovite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaB₂O₄·4H₂O
- Mohs hardness
- 3.5
- Density
- 2.14-2.22 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous to dull
- Transparency
- Opaque, translucent through thin edges
- Crystal system
- Triclinic
- Crystal habit
- Irregular grains
- Cleavage
- Perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A rare alteration product of hydrothermal boron minerals in skarn deposits
Where rockhounds find frolovite
Classic worldwide localities
- Novofrolovskoye copper deposit, near Krasnoturinsk, Turinsk district, Northern Ural Mountains, and in the Solongo boron deposit, Buryatia, Russia
- Sayak-IV boron deposit, northeast Balkhash region, Kazakhstan
- Fuka, near Bicchu, Okayama Prefecture, Japan
Field-hunting tip
Where it forms: A rare alteration product of hydrothermal boron minerals in skarn deposits. If you start seeing calciborite, calcite, gypsum in float, you are in the right ground. Typical habit: irregular grains. Train your eye for that shape before scanning the outcrop.
Common questions
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Find frolovite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
