Hydrochlorborite is a rare hydrated calcium borate chloride mineral typically found in saline evaporite deposits. Collectors usually look for its characteristic white, fibrous to radial crystal clusters associated with other borate minerals.
Is this hydrochlorborite?
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 hydrochlorborite with a known reference. Hydrochlorborite 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. Hydrochlorborite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Hydrochlorborite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: white, colorless.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: fibrous, radiated, or as delicate laths.
Often confused with
Hydrochlorborite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Luster reads vitreous on Hydrochlorborite and vitreous to earthy on Borax.
How to tell apart: Priceite is the harder of the two (Mohs 3-3.5 vs. 2); luster reads vitreous on Hydrochlorborite and dull on Priceite.
Often found alongside hydrochlorborite
Minerals reported to co-occur with hydrochlorborite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ca₂[B₃O₃(OH)₄]Cl·7H₂O
- Mohs hardness
- 2
- Density
- 2.14 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Fibrous, Radiated, Or as Delicate Laths
- Cleavage
- Perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Evaporite Deposits
- Typical price
- $50-250 for rare specimen
Where rockhounds find hydrochlorborite
Classic worldwide localities
- Kurnakov deposit, Russia
- Inder deposit, Kazakhstan
- Searles Lake, USA
Field-hunting tip
Look in evaporite deposits country — that is the host setting where hydrochlorborite typically forms. If you start seeing halite, borax, gypsum in float, you are in the right ground. Field specimens usually show a fibrous, radiated, or as delicate laths habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find hydrochlorborite on the map
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