Korshunovskite

Chemical formula: Mg<sub>2</sub>Cl(OH)<sub>3</sub>(H<sub>2</sub>O)<sub>3</sub>·H<sub>2</sub>O

Korshunovskite is a rare magnesium chloride, forming colorless, acicular crystals and fibrous aggregates, found in rock salt deposits.

## Characteristics Korshunovskite is a hydrated magnesium hydroxychloride. It most commonly occurs as colorless or white, silky fibrous aggregates. It also forms radial groupings and well-formed, acicular or bladed crystals, which can reach up to 2 cm in length. It is a transparent mineral with a vitreous luster. ## Physical Properties This mineral is very soft, with a Mohs hardness of only 2. It has a low density, approximately 1.77 g/cm³. It is brittle and exhibits perfect cleavage in one direction, which is evident in its fibrous nature. ## Colors and Varieties Korshunovskite is usually colorless or white. No colored varieties have been distinguished. ## History and Name The mineral was first described in 1982 by S. N. Malinko, I. M. Rumanova, and T. A. Stolyarova. Its name comes from the discovery locality – the Korshunovskoye iron ore deposit in the Irkutsk Oblast, Siberia, Russia. ## Applications Due to its rarity and small crystal size, korshunovskite has no industrial applications. It is solely an object of interest for collectors specializing in rare minerals.

Properties

Mohs hardness
2
Luster
Vitreous
Streak
White
Density
1.77
Cleavage
Perfect on {100}
Fracture
Uneven
Transparency
Transparent
Crystal system
Monoclinic

Diagnostic features

## Identification Korshunovskite can be identified by its characteristic, silky, fibrous or acicular aggregates. A key diagnostic feature is its solubility in water. It is very soft and light. ## Distinguishing from Similar Minerals It can be confused with other fibrous salt minerals, such as carnallite or bischofite, but differs from them in optical properties and precise chemical composition. In field conditions, differentiation without chemical tests is difficult. Fibrous zeolites or gypsum (selenite) are insoluble in water and significantly harder. ## Crystal Forms It forms elongated, acicular or bladed crystals, often grouped into radial or fibrous aggregates. Crystals are elongated along the crystallographic c-axis.

Geological environment

## Genesis Korshunovskite is a secondary mineral, forming in the oxidation zones of magnetite-borate deposits that intersect layers of salt rocks (evaporites). It forms as a result of the alteration of magnesium-borate minerals in a chloride-rich environment. ## Mineral Associations It most commonly co-occurs with halite, magnetite, szaibelyite, ludwigite, and other rare magnesium hydroxychlorides. ## Localities The most important and type locality is the Korshunovskoye iron ore deposit in the Irkutsk Oblast, Siberia, Russia. This is the only confirmed and well-documented locality for this mineral in the world.

Rarity

Very rare

For collectors

## Quality Criteria The most prized specimens are those with well-formed, transparent, acicular crystals, forming attractive radial aggregates. Crystal size and absence of mechanical damage are important. A contrasting matrix, e.g., with magnetite, enhances the visual value of the specimen. ## Popular Localities The Korshunovskoye deposit in Russia is the sole source of collector specimens. Specimens from this locality are the standard for this mineral.

Care and storage

## Cleaning Korshunovskite specimens are extremely sensitive to water, in which they dissolve. Cleaning is not recommended. If absolutely necessary, compressed air can be used to remove dust, but from a very long distance and with minimal force. ## What to Avoid Avoid all contact with water, water vapor, and high humidity, as the mineral is hygroscopic and easily soluble. Also, avoid chemicals, ultrasonics, and high temperatures. ## Storage Korshunovskite must be stored in a sealed, dry container, preferably with a desiccant (e.g., silica gel). It should be kept away from sources of heat and moisture.

Sources

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