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. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: brownish, brownish 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.
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
- 2.47 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Semitransparent
- Crystal system
- Cubic
- Crystal habit
- Tabular crystals, massive
- Cleavage
- Indistinct
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In fine-grained halite in a salt dome (Chalkar salt dome, Kazakhstan)
Where rockhounds find metaborite
Classic worldwide localities
- Chelkar salt dome, Ak-saı̆ Valley, Uralsk district, and at the Inder borate deposit, Kazakhstan
Field-hunting tip
Where it forms: In fine-grained halite in a salt dome (Chalkar salt dome, Kazakhstan). If you start seeing halite, anhydrite, kieserite in float, you are in the right ground. Typical habit: tabular crystals, massive. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify metaborite?+
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What rocks look like metaborite?+
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Find metaborite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
