Hexahydroborite is a rare calcium borate mineral that typically forms as delicate, radial fibrous aggregates or thin crusts in evaporite deposits. Due to its solubility and structural instability, it is primarily sought after by advanced collectors of borate minerals and is rarely seen in general collections.
Is this hexahydroborite?
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 hexahydroborite with a known reference. Hexahydroborite sits at Mohs 2 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Hexahydroborite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Hexahydroborite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: white, colorless.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: radial aggregates, fibrous, crusts.
Often confused with
Hexahydroborite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Priceite is the harder of the two (Mohs 3-3.5 vs. 2); luster reads vitreous on Hexahydroborite and dull on Priceite.
How to tell apart: Howlite is the harder of the two (Mohs 3.5 vs. 2); luster reads vitreous on Hexahydroborite and subvitreous on Howlite.
How to tell apart: Luster reads vitreous on Hexahydroborite and pearly on Veatchite.
Often found alongside hexahydroborite
Minerals reported to co-occur with hexahydroborite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaB₂O₄·6H₂O
- Mohs hardness
- 2
- Density
- 1.89 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Radial Aggregates, Fibrous, Crusts
- Cleavage
- Perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Evaporite Deposits
- Typical price
- $20-150 for small specimens
Where rockhounds find hexahydroborite
Classic worldwide localities
- Solongo mine, Buryatia, Russia
- Inder boron deposit, Kazakhstan
Field-hunting tip
Look in evaporite deposits country — that is the host setting where hexahydroborite typically forms. If you start seeing borax, kernite, ulexite in float, you are in the right ground. Field specimens usually show a radial aggregates, fibrous, crusts habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find hexahydroborite on the map
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