Hydroboracite is an uncommon borate mineral typically found as delicate, fibrous, or acicular white masses within evaporite basins. Collectors often look for it as part of mineral assemblages in desert regions, where it forms distinct, needle-like spray habits that are prized for their aesthetic quality.
Is this hydroboracite?
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 hydroboracite with a known reference. Hydroboracite 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. Hydroboracite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Hydroboracite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: white, colorless, gray.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: acicular crystals, fibrous radiating sprays, massive.
Often confused with
Hydroboracite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Hydroboracite is noticeably harder (Mohs 4 vs. 2.5); luster reads vitreous on Hydroboracite and silky on Ulexite.
How to tell apart: Luster reads vitreous on Hydroboracite and dull on Priceite.
How to tell apart: Luster reads vitreous on Hydroboracite and subvitreous on Howlite.
Often found alongside hydroboracite
Minerals reported to co-occur with hydroboracite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaMgB₆O₁₁·6H₂O
- Mohs hardness
- 4
- Density
- 2.1 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Acicular Crystals, Fibrous Radiating Sprays, Massive
- Cleavage
- Perfect
- Rarity
- Uncommon
- Uses
- Collector
- Host rock
- Evaporite Deposits
- Typical price
- $10-60 for small mineral specimens
Where rockhounds find hydroboracite
Classic worldwide localities
- Inder deposit, Kazakhstan
- Death Valley, California, USA
- Argentina
- Turkey
Field-hunting tip
Look in evaporite deposits country — that is the host setting where hydroboracite typically forms. If you start seeing ulexite, colemanite, glauberite in float, you are in the right ground. Field specimens usually show a acicular crystals, fibrous radiating sprays, massive habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find hydroboracite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
