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 4 — 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: monoclinic. 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 4 vs. 1); luster reads vitreous on Metaborite and pearly on Sassolite.
How to tell apart: Metaborite is noticeably harder (Mohs 4 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
- 4
- Density
- 2.5 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Tabular Crystals, Massive
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Fumarolic Deposits
- Typical price
- $50-300 per specimen
Where rockhounds find metaborite
Classic worldwide localities
- Tuscany, Italy
- Sassolino, Italy
Field-hunting tip
Look in fumarolic deposits country — that is 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
How do you identify metaborite?+
Where is metaborite found?+
How much is metaborite worth?+
What rocks look like metaborite?+
What minerals are found with metaborite?+
What kind of rock does metaborite form in?+
What is metaborite used for?+
Find metaborite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
