Kernite is a rare sodium borate mineral typically found as large, colorless to white prismatic crystals in evaporite deposits. It is known to dehydrate upon exposure to air, often altering into a white powder of tincalconite, so specimens should be kept in sealed containers. It is most famous for its occurrences in the Kramer borate deposit in California.
Is this kernite?
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 kernite with a known reference. Kernite sits at Mohs 2.5-3 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Kernite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Kernite typically shows a vitreous to pearly luster.
- 4Match the color rangeCompare against the expected color range: colorless, white, gray.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic, massive, granular.
Often confused with
Kernite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside kernite
Minerals reported to co-occur with kernite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Na₂B₄O₆(OH)₂·3H₂O
- Mohs hardness
- 2.5-3
- Density
- 1.95 g/cm³
- Streak
- White
- Luster
- Vitreous to Pearly
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic, Massive, Granular
- Cleavage
- Perfect in Two Directions
- Rarity
- Uncommon
- Uses
- Industrial, Collector
- Host rock
- Evaporite Deposits in Lacustrine Basins
- Typical price
- $10-60 for small cabinet specimens
Where rockhounds find kernite
Classic worldwide localities
- Boron, California, USA
- Tincalayu, Argentina
- Kirka, Turkey
Field-hunting tip
Look in evaporite deposits in lacustrine basins country — that is the host setting where kernite typically forms. If you start seeing borax, ulexite, colemanite in float, you are in the right ground. Field specimens usually show a prismatic, massive, granular habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find kernite on the map
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