Kernite - Encyclopedia

    Class : Carbonates, nitrates, borates
    Subclass : Borates
    Crystal system : Monoclinic
    Chemistry : Na2B4O6(OH)2 3H2O
    Rarity : Quite common

Kernite is, like the vast majority of borates, an evaporitic mineral (formed by evaporation of salt lakes in a desert environment). The waters of these lakes contain large quantities of borated brines linked to volcanic phenomena. In its salt lake deposits, kernite is associated with numerous salts: borates (ulexite, borax, colemanite, etc...), halite, glauberite, thenardite, gypsum, etc... It must its name to its location of discovery : the Kramer deposit in Kern County (California). Kernite occurs in striated crystals or cleavable masses, sometimes very leafy, chalky white, slowly soluble in cold water, of low density (1.9) like most borates. Its shine is glassy, satiny on the cleavage. Kernite is currently the most important boron ore. It is converted into borax which is the commercial form of boron.

Main photo : Kernite from Rio Tinto Borax Mine, California, USA © Pedro Gonzales

Kernite in the World

Exceptional kernite crystals come from the large Californian Boron deposit where they are derived from borax by increased pressure and temperature, they measure up to 2.5 meters. This deposit contains several million tons of kernite. Kernite is also found in Furnace Creek (Death Valley, California), as well as in evaporite deposits in Turkey (Kirka) and Argentina (Tincalayu).

Kernite in France

Kernite is not present in the French underground.


Twins have been known on {011}.

Fakes and treatments

No fakes recorded for this mineral species.

Hardness : 2.5
Density : 1.90
Fracture : Irregular
Streak : White

TP : Transparent
RI : 1.454 to 1.488
Birefringence : 0.034
Optical character : Biaxial -
Pleochroism : None
Fluorescence : None

Solubility : Water, acids

Magnetism : NoneRadioactivity : None


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