Kurnakovite Value, Price, and Jewelry Information

view gemstone encyclopedia

Rectangular radiant-cut kurnakovite, 4.36 cts, 13.5 x 9 mm, Boron, California. © The Gem Trader. Used with permission.

Kurnakovite is difficult to cut, inadvisable to wear, and usually colorless. Consequently, faceted specimens are extremely rare.

Kurnakovite Information

Data Value
Name Kurnakovite
Is a Variety of Inderite
Crystallography Triclinic. Crystals large and blocky, often in clusters; large cleavable masses; aggregates.
Refractive Index 1.488-1.525
Colors Colorless, with a white surface coating.
Luster Vitreous
Hardness 2.5-3
Fracture Conchoidal
Specific Gravity 1.78-1.85
Birefringence 0.027-0.036
Cleavage Good 1 direction
Luminescence None
Luminescence Present No
Transparency Translucent to transparent
Absorption Spectrum Not diagnostic
Formula Mg2B611  · 15H2O.
Pleochroism None
Optics a = 1.488-1.491 ; β = 1.508-1.511;  γ = 1.515-1.525. Biaxial (-), 2V= 80°.
Optic Sign Biaxial -
Etymology After N. S. Kurnakov, Russian mineralogist and chemist.
Occurrence Borate deposits in arid areas.
kurnakovite crystal

Kurnakovite crystal, collected by Robert Herod, 1988, from Boron, California. From the mineral collection of Brigham Young University, Department of Geology, Provo, Utah. Photo by Andrew Silver. Public Domain.


Kurnakovite belongs to the inderite mineral group, which includes the species also known as inderite. Inderite has a monoclinic crystal structure, while kurnakovite is its triclinic dimorph. They share the same chemistry as well as general appearance and limitations as jewelry stones. Inderites are more likely than kurnakovites to be used as jewelry stones, but only because the material is somewhat more available.

Kurnakovites have a hardness of only 2.5-3. This means some specimens could be scratched by a coin, and they can all easily be scratched by household dust (with a hardness of 7). They also have perfect cleavage, which makes them liable to split if struck on their internal cleavage plane.

If those weren’t enough reasons to dissuade faceters, kurnakovites are also soluble in warm acids. Thus, wearing these stones as jewelry would be inadvisable. On the other hand, faceted or cabbed specimens would make interesting collectible items for display.


Scientists have synthesized kurnakovites and inderites for research purposes. However, there’s no known use or demand for this material as jewelry.


No known treatments.


Boron, Kern County, California produces crystals to 24 inches across and large masses.

Other notable sources include the following:

  • Argentina; China; Inder Lake, Kazakhstan; Turkey.
kurnakovite - Argentina

Kurnakovite crystal, 3 x 3 x 2.4 cm, Tincalayu mine, Salar del Hombre Muerto, Los Andes department, Salta Province, Argentina. Photo by Raúl Jorge Tauber Larry. Public Domain.

Stone Sizes

Kurnakovites occur in large sizes. The California material could yield stones of several hundred carats from large transparent masses or cleavages.


Clean kurnakovites only with a soft brush, mild detergent, and warm water. Reserve these specimens for display. For more recommendations, consult our gemstone jewelry care guide.

Ready to learn how to identify gems on your own?

Join our mailing list below to download a FREE gem ID checklist tutorial. See what’s inside…

• Discover the 17 practical steps to gemstone identification (even if you’re just getting started with gemology)

• Learn how you can use specific tools to gather data, make observations & arrive at an accurate ID

• Explore a range of gemological tests… not only will you get familiar with the process but also time-saving shortcuts!