Biringuccite is a rare borate mineral typically found as white, platy, or micaceous aggregates in geothermal or evaporite environments. It is often identified by its association with other borate species and its specific paragenesis in fumarolic areas, though it is quite difficult to distinguish macroscopically from similar borates without XRD analysis.
Is this biringuccite?
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 biringuccite with a known reference. Biringuccite sits at Mohs 2.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Biringuccite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Biringuccite typically shows a pearly luster.
- 4Match the color rangeCompare against the expected color range: white, colorless.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: platy crystals, aggregates, crusts.
Often confused with
Biringuccite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Luster reads pearly on Biringuccite and vitreous to earthy on Borax.
How to tell apart: Luster reads pearly on Biringuccite and silky on Ulexite.
How to tell apart: Probertite is the harder of the two (Mohs 3.5 vs. 2.5); luster reads pearly on Biringuccite and vitreous on Probertite.
Often found alongside biringuccite
Minerals reported to co-occur with biringuccite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Na₄B₁₀O₁₆(OH)₂·5H₂O
- Mohs hardness
- 2.5
- Density
- 2.05 g/cm³
- Streak
- White
- Luster
- Pearly
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Platy Crystals, Aggregates, Crusts
- Cleavage
- Perfect On {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Fumarolic Deposits, Evaporite Deposits
- Typical price
- $20-100 per specimen
Where rockhounds find biringuccite
Classic worldwide localities
- Larderello, Tuscany, Italy
- Sarsana, Turkey
- Boron, California, USA
Field-hunting tip
Look in fumarolic deposits, evaporite deposits country — that is the host setting where biringuccite typically forms. If you start seeing borax, ulexite, gypsum in float, you are in the right ground. Field specimens usually show a platy crystals, aggregates, crusts habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find biringuccite on the map
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