Kurnakovite is a hydrated

borate A borate is any of several boron oxyanions, negative ions consisting of boron and oxygen, such as orthoborate , metaborate , or tetraborate ; or any salt with such anions, such as sodium metaborate, and disodium tetraborate . The name a ...

magnesium Magnesium is a chemical element with the symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 of the periodic ...

with the chemical composition MgB₃O₃(OH)₅·5H₂O. It is a member of the

inderite Inderite, also known as Lesserite, is a mineral that was named after its source, the Inder lake, near the Inder Mountains in Kazakhstan. The samples were described in English by the soviet mineralogist Boldyreva in 1937. It is a rare secondary mi ...

group and is a

triclinic 180px, Triclinic (a ≠ b ≠ c and α ≠ β ≠ γ ) In crystallography, the triclinic (or anorthic) crystal system is one of the 7 crystal systems. A crystal system is described by three basis vectors. In the triclinic system, the crystal i ...

dimorph In materials science, polymorphism describes the existence of a solid material in more than one form or crystal structure. Polymorphism is a form of isomerism. Any crystalline material can exhibit the phenomenon. Allotropy refers to polymorphism ...

of the

monoclinic In crystallography, the monoclinic crystal system is one of the seven crystal systems. A crystal system is described by three vectors. In the monoclinic system, the crystal is described by vectors of unequal lengths, as in the orthorhombic ...

inderite.

Discovery and occurrence

Kurnakovite, was first described by Godlevsky in 1940 for an occurrence in the Inder lake borate deposits in

Atyrau Province Atyrau Region ( kk, Атырау облысы / ; russian: Атырауская область) formerly known as Guryev Region (russian: Гурьевская область) until 1991, is one of the regions of Kazakhstan, in the west of the co ...

Kazakhstan Kazakhstan, officially the Republic of Kazakhstan, is a transcontinental country located mainly in Central Asia and partly in Eastern Europe. It borders Russia Russia (, , ), or the Russian Federation, is a transcontinental coun ...

, and is named for Russian mineralogist and chemist

Nikolai Semenovich Kurnakov Nikolai Semyonovich Kurnakov (russian: Николай Семёнович Курнаков; 6 December 1860 – 19 March 1941) was a Russian chemist, who is internationally recognized as the originator of physical chemistry, physicochemical analys ...

(1860–1941). In addition to the

type locality Type locality may refer to: * Type locality (biology) * Type locality (geology) See also * Local (disambiguation) * Locality (disambiguation) {{disambiguation ...

in Kazakhstan, kurakovite has also been reported from the Zhacang-Caka brine lake,

Tibet Tibet (; ''Böd''; ) is a region in East Asia, covering much of the Tibetan Plateau and spanning about . It is the traditional homeland of the Tibetan people. Also resident on the plateau are some other ethnic groups such as Monpa people, ...

; the Kirka borate deposit, Kiitahya Province,

Turkey Turkey ( tr, Türkiye ), officially the Republic of Türkiye ( tr, Türkiye Cumhuriyeti, links=no ), is a list of transcontinental countries, transcontinental country located mainly on the Anatolia, Anatolian Peninsula in Western Asia, with ...

; the Kramer borate deposit, Boron,

Kern County, California Kern County is a county located in the U.S. state of California. As of the 2020 census, the population was 909,235. Its county seat is Bakersfield. Kern County comprises the Bakersfield, California, Metropolitan statistical area. The county ...

;

Death Valley National Park Death Valley National Park is an American national park that straddles the California–Nevada border, east of the Sierra Nevada. The park boundaries include Death Valley, the northern section of Panamint Valley, the southern section of Eure ...

Inyo County, California Inyo County () is a county in the eastern central part of the U.S. state of California, located between the Sierra Nevada and the state of Nevada. In the 2020 census, the population was 19,016. The county seat is Independence. Inyo County i ...

; and the Tincalayu borax deposit, Salar del Hombre Muerto,

Salta Province Salta () is a province of Argentina, located in the northwest of the country. Neighboring provinces are from the east clockwise Formosa, Chaco, Santiago del Estero, Tucumán and Catamarca. It also surrounds Jujuy. To the north it borders Boli ...

Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, t ...

Properties

Kurnakovite has

- pinacodial crystallography. It forms as rough, prismatic

crystals A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macros ...

, typically in dense aggregates. Kurnakovite has distinct

cleavage Cleavage may refer to: Science * Cleavage (crystal), in mineralogy and materials science, a process of splitting a crystal * Cleavage (geology), the foliation perpendicular to stress as a result of ductile deformation * Cleavage (embryo), in emb ...

and a

conchoidal fracture Conchoidal fracture describes the way that brittle materials break or fracture when they do not follow any natural planes of separation. Mindat.org defines conchoidal fracture as follows: "a fracture with smooth, curved surfaces, typically sli ...

. Its

tenacity Tenacity may refer to: * Tenacity (psychology), having persistence in purpose * Tenacity (mineralogy) a mineral's resistance to breaking or deformation * Tenacity (herbicide), a brand name for a selective herbicide * Tenacity (textile strength) * ...

brittle A material is brittle if, when subjected to stress, it fractures with little elastic deformation and without significant plastic deformation. Brittle materials absorb relatively little energy prior to fracture, even those of high strength. ...

and it ranges between 2.5 – 3 on the

Mohs hardness The Mohs scale of mineral hardness () is a qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of various minerals through the ability of harder material to scratch softer material. The scale was introduced in 1812 by the ...

scale. It is not soluble in water, though it will start dissolving in warm acid. Kurnakovite is usually colorless or white and either transparent or translucent. It has a vitreous, pearly luster and a

refractive index In optics, the refractive index (or refraction index) of an optical medium is a dimensionless number that gives the indication of the light bending ability of that medium. The refractive index determines how much the path of light is bent, o ...

of between 1.488 - 1.525.

References

{{Commons category Magnesium minerals Nesoborates Triclinic minerals Minerals in space group 2