Kurnakovite is a hydrated borate of magnesium with the chemical composition MgB3O3(OH)5·5H2O.

[3] Kurnakovite, was first described by Godlevsky in 1940 for an occurrence in the Inder lake borate deposits in Atyrau Province, Kazakhstan, and is named for Russian mineralogist and chemist Nikolai Semenovich Kurnakov (1860–1941).

[2] In addition to the type locality in Kazakhstan, kurakovite has also been reported from the Zhacang-Caka brine lake, Tibet; the Kirka borate deposit, Kiitahya Province, Turkey; the Kramer borate deposit, Boron, Kern County, California; Death Valley National Park, Inyo County, California; and the Tincalayu borax deposit, Salar del Hombre Muerto, Salta Province, Argentina.

It forms as rough, prismatic crystals, typically in dense aggregates.

It is not soluble in water, though it will start dissolving in warm acid.