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Na2[B4O6(OH)2] · 3H2O
Colourless to white.
After Kern County, California, USA, where it was first discovered.
This page provides mineralogical data about Kernite.

Classification of Kernite

Approved, 'Grandfathered' (first described prior to 1959)

D : Tetraborates
B : Ino-tetraborates

4 : Tetraborates

9 : Borates
1 : Borates of the alkalis and boric acid

Kernite in petrology

An essential component of (items highlighted in red)

Occurrences of Kernite

Type Occurrence of Kernite

Geological Setting of Type Material:
Metamorphosed bedded borate deposit in clay-shales.
Associated Minerals at Type Locality:

Physical Properties of Kernite

Diaphaneity (Transparency):
Satinly on fibrous cleavages
Colourless to white.
Hardness (Mohs):
On {100} perfect; {001} less perfect; on {201} fair. NOTE: The cleavable masses exhibit a simulated fibrous structure due to development of excellent cleavages. Cleavage fragments usually bent or warped around [001].
1.906(3) g/cm3 (Measured)    1.905 g/cm3 (Calculated)

Crystallography of Kernite

Crystal System:
Class (H-M):
2/m - Prismatic
Space Group:
Cell Parameters:
a = 7.0172(2) Å, b = 9.1582(2) Å, c = 15.6774(5) Å
β = 108.861(2)°
a:b:c = 0.766 : 1 : 1.712
Unit Cell Volume:
V 953.41 ų (Calculated from Unit Cell)
Crystals nearly equant, commonly slightly elongated [100] and deeply striated [010], with irregular form development. Wedge-shaped at times or rounded due to repetition of faces. Cleavable masses. Massive.
On {011}.
X-Ray Powder Diffraction:
Image Loading

Radiation - Copper Kα
Data Set:
Data courtesy of RRUFF project at University of Arizona, used with permission.

Optical Data of Kernite

Biaxial (-)
RI values:
nα = 1.454 nβ = 1.472 nγ = 1.488
Measured: 80° , Calculated: 84°
Max Birefringence:
δ = 0.034
Image shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:
r > v distinct

Chemical Properties of Kernite

Na2[B4O6(OH)2] · 3H2O
All elements listed in formula:

Relationship of Kernite to other Species

9.1.4BiringucciteNa2B5O8(OH) · H2O
9.1.5NasiniteNa2[B5O8(OH)] · 2H2O
9.1.7EzcurriteNa4B10O17 · 7H2O
9.1.8TincalconiteNa2(B4O7) · 5H2O
9.1.9BoraxNa2(B4O5)(OH)4 · 8H2O
9.1.11SborgiteNa[B5O6(OH)4] · 3H2O
9.1.12AristarainiteNa2MgB12O20 · 8H2O
9.1.13SantiteK[B5O6(OH)4] · 2H2O
9.1.14Larderellite(NH4)B5O7(OH)2 · H2O
9.1.15Ammonioborite(NH4)2[B5O6(OH)4]2 · H2O

Other Names for Kernite

Name in Other Languages:

Other Information

Thermal Behaviour:
Alters to metakernite (Na2B4O7·5H2O) upon heating to 100° - 120° C, as a non-reversible change.
Other Information:
Slowly soluble in cold water, readily so in hot water.

Alters to tincalconite upon dehydration.
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for Kernite

Reference List:
Palmer (1927) Engineering and Mining Journal: 123: 494 (as rasorite).

Schaller, Waldemar Theodore (1927), Kernite, a new sodium borate: American Mineralogist: 12: 24-25.

Schaller (1930) USGS Professional Paper 158: 137.

Garrido, J. (1932), Symmetrie und Raumgruppe des Kernite: Zeitschr. Kristallographie, band 82: 468-470.

Minder (1935) Zeitschrift für Kristallographie, Mineralogie und Petrographie, Leipzig: 92: 301.

Minder, Schulz and Deckert (1935) Die Naturwissenschaften, Berlin: 23: 832.

Schaller, Waldemar Theodore (1936), The origin of kernite and borax in the Kramer borate field, California (abstract) American Mineralogist: 21: 192.

Menzel and Schulz (1940) Zeitschrift für anorganische und allgemeine Chemie, Hamburg, Leipzig: 245: 157.

Amorós (1947) Inst. Invest. Geol. Barcelona, no. 7.

Palache, C., Berman, H., & Frondel, C. (1951), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana, Yale University 1837-1892, Volume II. John Wiley and Sons, Inc., New York, 7th edition, revised and enlarged: 335-337.

Muessig, S. & R.D. Allen (1957), The hydration of kernite (Na3B4O7·4H2O), American Mineralogist: 42: 699-701.

American Mineralogist (1973): 58: 21-31.

Grew, E.S., and Anovitz, L.M. (1996) BORON: Mineralogy, Petrology and Geochemistry, second edition, as revised (2002).

Anthony, J.W., Bideaux, R.A., Bladh, K.W., and Nichols, M.C. (2003) Handbook of Mineralogy, Volume V. Borates, Carbonates, Sulfates. Mineral Data Publishing, Tucson, AZ, 813pp.: 352.

Internet Links for Kernite URL:
Please feel free to link to this page.

Localities for Kernite

map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
(TL) indicates type locality for a valid mineral species. (FRL) indicates first recorded locality for everything else. ? indicates mineral may be doubtful at this locality. All other localities listed without reference should be considered as uncertain and unproven until references can be found.
  • Buckley Island quadrangle
Fitzpatrick, J.J., Muhs, D.R. (1990) Antarctic Journal of the United States, 24 (5), 63-65.
  • Salta
    • Los Andes department
      • Salar del Hombre Muerto
Am Min 58:308-313; Alonso, R. N. (1999). On the origin of La Puna borates. Acta geológica hispánica, 34(2), 141-166.; CAHIT HELVACI & RICARDO N. ALONSO (2000) Borate Deposits of Turkey and Argentina; A Summary and Geological Comparison. Turkish Journal of Earth Sciences, 9:1-27.
Kezao Chen (1992): Quaternary Sciences 3(8), 193-202
  • Central Anatolia Region
    • Eskişehir Province
      • Kirka
CAHIT HELVACI & RICARDO N. ALONSO (2000) Borate Deposits of Turkey and Argentina; A Summary and Geological Comparison. Turkish Journal of Earth Sciences, Vol. 9, 2000, pp. 1-27
  • California
    • Kern Co.
      • Kramer District (Kramer Borate District)
Rock Currier collection
Schaller, Waldemar Theodore (1927), Kernite, a new sodium borate: American Mineralogist: 12: 24; Eakle, Arthur Starr (1929), Probertite, a new borate: American Mineralogist: 14: 427; Morgan, V. and Erd, R.C. (1969) Minerals of the Kramer borate district, California California Division of Mines and Geology Mineral Information Service: 22(9): 147-148, 153, 169; Pemberton, H. Earl (1983), Minerals of California; Van Nostrand Reinholt Press: 259.
Meier, D. C., Davis, J. M., & Vicenzi, E. P. (2011). An examination of kernite (Na 2 B 4 O 6 (OH) 2· 3H 2 O) using X-ray and electron spectroscopies: quantitative microanalysis of a hydrated low-z mineral. Microscopy and Microanalysis, 17(05), 718-727.
Frondel C, Morgan V (1956) Inderite and gerstleyite from the Kramer borate district, Kern County, California. American Mineralogist 41, 839-843
Boslough, M. B., Weldon, R. J., & Ahrens, T. J. (1980). Impact-induced water loss from serpentine, nontronite and kernite. In Lunar and Planetary Science Conference Proceedings (Vol. 11).
            • West Baker
Am Min 49:543-555
        • Rich
American Mineralogist (1927): 12: 24-25.
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