Metaborite is a rare borate mineral typically found in volcanic fumarole environments. It is best identified by its occurrence in white, crust-like masses or small tabular crystals alongside other borate species like sassolite.
Is this metaborite?
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 metaborite with a known reference. Metaborite sits at Mohs 5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Metaborite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Metaborite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: white, colorless.
- 5Look at form & habitCrystal system: cubic. Typical habit: tabular crystals, massive.
Often confused with
Metaborite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Metaborite is noticeably harder (Mohs 5 vs. 1); luster reads vitreous on Metaborite and pearly on Sassolite.
How to tell apart: Metaborite is noticeably harder (Mohs 5 vs. 2-2.5); luster reads vitreous on Metaborite and vitreous to earthy on Borax.
Often found alongside metaborite
Minerals reported to co-occur with metaborite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- HBO₂
- Mohs hardness
- 5
- Density
- 2.5 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Cubic
- Crystal habit
- Tabular Crystals, Massive
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Fumarolic Deposits
Where rockhounds find metaborite
Classic worldwide localities
- Chelkar salt dome, Uralsk district, and at the Inder borate deposit, Kazakhstan
Field-hunting tip
Look in fumarolic deposits country, the host setting where metaborite typically forms. If you start seeing sassolite, borax, gypsum in float, you are in the right ground. Field specimens usually show a tabular crystals, massive habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find metaborite on the map
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