Boracite is a rare magnesium borate mineral typically found in evaporite sequences. It is famous among collectors for forming remarkably sharp, pseudo-cubic crystals that appear isometric despite their orthorhombic internal structure.
Is this boracite?
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 boracite with a known reference. Boracite sits at Mohs 7-7.5, 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 adamantine.
- 4Match the color rangeCompare against the expected color range: colorless, white, gray, yellow, green, blue, blue green.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: crystalline, disseminated.
Often confused with
Boracite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside boracite
Minerals reported to co-occur with boracite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Mg₃B₇O₁₃Cl
- Mohs hardness
- 7-7.5
- Density
- 2.91-3.10 g/cm³
- Streak
- White
- Luster
- Vitreous to adamantine
- Transparency
- Transparent to translucent
- Crystal system
- Orthorhombic
- Crystal habit
- Crystalline, disseminated
- Cleavage
- None
- Rarity
- Uncommon
- Uses
- Collector, Scientific study
- Host rock
- An uncommon component of bedded sedimentary salt and potash deposits of marine origin, the boron probably derived from nearby volcanic activity
Where rockhounds find boracite
Classic worldwide localities
- Choctaw salt dome, Iberville Parish, Louisiana, and the Louann Salt Formation, Clarke Co., Alabama, USA
- Lüneburg, 40 km south-southeast of Hamburg, Lower Saxony, Germany
- Saxony-Anhalt, in the Stassfurt-Westeregeln-Bernburg district, at the Douglashall, Berlepsch, Solvayhall, Wilhelmshall, Germany
- Thuringia, from Bischofferode, in the Glückauf mine, Sondershausen, Germany
- Lunéville, Meurthe-et-Moselle, France
- Boulby potash mine, northwest of Whitby, Yorkshire, England
Field-hunting tip
Where it forms: An uncommon component of bedded sedimentary salt and potash deposits of marine origin, the boron probably derived from nearby volcanic activity. If you start seeing anhydrite, gypsum, halite in float, you are in the right ground. Typical habit: crystalline, disseminated. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify boracite?+
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What rocks look like boracite?+
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Find boracite on the map
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