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 2.5, 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 to dull.
- 4Match the color rangeCompare against the expected color range: 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.
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
- Ca₂B₄O₄Cl(OH)₇·7H₂O
- Mohs hardness
- 2.5
- Density
- 1.83-1.85 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous to dull
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Fibrous, radiated, or as delicate laths
- Cleavage
- On {001}, good
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A rare dry-season evaporite mineral in playa sediment (Salar Carcote, Chile)
Where rockhounds find hydrochlorborite
Classic worldwide localities
- Salar Carote, Antofagasta, Chile
Field-hunting tip
Where it forms: A rare dry-season evaporite mineral in playa sediment (Salar Carcote, Chile). If you start seeing ulexite, halite, gypsum in float, you are in the right ground. Typical habit: fibrous, radiated, or as delicate laths. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify hydrochlorborite?+
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Find hydrochlorborite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
