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, 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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