Kurnakovite: Gemstone Information
Kurnakovite is MgB3O3(OH)55H2O and forms colourless transparent roughly prismatic crystals of the triclinic system with hardness 2.5–3 and SG near 1.83. The RI for the alpha, beta and gamma rays is 1.488–1.491,1.508–1.510, 1.515–1.525, biaxial negative with birefringence 0.030.Kurnakovite occurs in lake-bed borate deposits and the occasional faceted specimen will probably have come from Boron, Kern County,California, USA. Kurnakovite is dimorphous with inderite (q.v.), found at Inder Lake borate deposit, Kazakhstan.