Galuskinite

Chemical formula: Ca₇(SiO₄)₃(CO₃)

Galuskinite is a rare calcium silicate from the hatrurite group, forming colorless or white, granular aggregates, discovered in Russia.

## Characteristics Galuskinite is a mineral belonging to the silicates, specifically to the hatrurite group. It occurs as anhedral (irregularly shaped) grains up to 0.5 mm in size, which form dense, granular aggregates. It is typically colorless, white, or light gray and transparent. Its appearance is inconspicuous, and identification requires specialized research methods. ## Physical Properties This mineral is characterized by a hardness of 5 on the Mohs scale, placing it on par with apatite. It has a vitreous luster and a white streak. Its density, calculated from crystallographic data, is 3.096 g/cm³. It exhibits cleavage in three directions. ## Colors and Varieties Galuskinite is usually colorless, white, or takes on pale gray hues. No colored or commercial varieties have been distinguished. ## History and Name The mineral's name honors Russian mineralogists, Irina and Evgeny Galuskin, for their contributions to the study of minerals from the hatrurite and larnite groups. It was approved as a new mineral species by the International Mineralogical Association (IMA) in 2010 (IMA2010-037). The type locality where it was first identified is the Birkhin gabbro massif in the Irkutsk Oblast, Russia.

Properties

Mohs hardness
5
Luster
Vitreous
Streak
White
Density
3.096
Cleavage
on {001}, {100} and {010}
Fracture
Irregular/Uneven
Transparency
Transparent
Crystal system
Monoclinic

Diagnostic features

## Identification Identifying galuskinite based on macroscopic features is practically impossible. It occurs as very fine, inconspicuous grains within the rock. Definitive identification requires advanced analytical techniques, such as X-ray diffraction (XRD) and chemical microanalysis (EDS/WDS). ## Distinguishing from Similar Minerals It can be confused with other colorless or white minerals found in similar parageneses, such as calcite, larnite, hatrurite, or other calcium silicates. Differentiation is possible only through chemical and crystallographic analysis. ## Crystal Forms Galuskinite forms irregularly shaped (anhedral) grains that coalesce into massive, granular aggregates. Well-formed, single crystals are not observed.

Geological environment

## Genesis Galuskinite forms under conditions of high-temperature contact metamorphism. At the type locality (Birkhin massif), it was found in xenoliths of carbonate rocks that were thermally altered by a gabbro intrusion. It is a product of reactions between carbonate rocks and silica at very high temperatures. ## Mineral Associations This mineral coexists with other rare high-temperature minerals, such as larnite, brownmillerite, mayenite, srebrodolskite, hatrurite, as well as perovskite, calcite, and members of the spinel group. ## Localities The only confirmed and described occurrence of galuskinite in the world is its type locality – the Birkhin (Ozernovskii) gabbro massif near Lake Baikal, in the Irkutsk Oblast, Russia.

Rarity

Extremely rare

For collectors

## Quality Criteria Due to its extreme rarity and microscopic nature, the collector's value of galuskinite specimens is not assessed based on typical criteria such as color or crystal size. The most valuable specimens are those from the type locality, with rich aggregates of galuskinite grains, confirmed by scientific analysis. The presence of rare associated minerals increases its value.

Care and storage

## Cleaning Due to its rarity and small grain size, galuskinite specimens usually occur in the host rock and do not require cleaning. If necessary, compressed air can be used to remove dust. Mechanical methods that could damage the fine grains should be avoided. ## What to Avoid Galuskinite, as a carbonate-silicate, can react with strong acids. Contact with chemicals, ultrasound, and sudden temperature changes should be avoided. Store away from moisture. ## Storage Specimens should be stored under stable conditions, in closed display boxes, to protect them from dust and mechanical damage. Due to its rarity, each specimen should be properly labeled with its locality.

External references

Sources

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