Genplesite

Chemical formula: Ca<sub>3</sub>Sn<sup>4+</sup>(S<sup>6+</sup>O<sub>4</sub>)<sub>2</sub>(OH)<sub>6</sub>·3H<sub>2</sub>O

Genplesite is a very rare tin and calcium sulfate, forming colorless, tabular crystals with a hexagonal outline.

## Characteristics Genplesite is a hydrated tin and calcium sulfate, belonging to the fleischerite group. This mineral forms very small, colorless, tabular crystals with a hexagonal outline, usually not exceeding 0.2 mm. These crystals often occur in radial or randomly oriented aggregates, growing on other minerals. ## Physical Properties Genplesite crystals exhibit a vitreous luster. Due to the small size of the crystals, many physical properties, such as hardness or density, have not been precisely determined. The density calculated based on the chemical formula and unit cell parameters is 2.81 g/cm³. ## Colors and Varieties Genplesite is colorless and does not form colored varieties. ## History and Name The mineral's name honors Gennadiy Nikolaevich Pleskach (born 1950), a Russian geologist and mineral collector from Petropavlovsk-Kamchatskiy, who found the first samples of this mineral. Genplesite was approved as a new mineral species by the International Mineralogical Association (IMA) in 2013 (IMA2013-067).

Properties

Mohs hardness
2
Luster
Vitreous
Streak
White
Density
2.81
Cleavage
Perfect on {0001}
Fracture
Uneven
Transparency
Transparent
Crystal system
Trigonal

Diagnostic features

## Identification Identification of genplesite is possible almost exclusively using advanced analytical methods, such as Raman spectroscopy or electron microprobe chemical analysis (EDS/WDS). Visually, it is characterized by its occurrence as very small, colorless, hexagonal tabular crystals in a specific fumarolic environment. ## Distinguishing from Similar Minerals It can be confused with other colorless sulfates found in the same environment, such as gypsum or anhydrite. Differentiation requires specialized studies, as genplesite is the only known tin sulfate from this locality. ## Crystal Forms Genplesite forms thin, tabular crystals with a hexagonal outline. They occur as single, dispersed crystals or form small, radial aggregates.

Geological environment

## Genesis Genplesite is a fumarolic mineral. It forms as a result of the sublimation of volcanic gases in active fumarole zones, crystallizing at temperatures of approximately 100-120°C. It is a product of the reaction of sulfur- and tin-rich gases with surrounding volcanic rocks. ## Mineral Associations This mineral co-occurs with other fumarolic minerals, such as gypsum, anhydrite, hematite, and various halides. ## Localities The only confirmed locality for genplesite in the world is its type locality – the Yadovitaya fumarole field on the second cinder cone of the Northern Breakthrough of the Great Fissure Tolbachik Eruption on Tolbachik volcano, Kamchatka, Russia.

Rarity

Extremely rare

For collectors

## Quality Criteria As a "micromount" type mineral, the collector's value of genplesite depends on the richness of the aggregates, the size (though always microscopic) and sharpness of the crystals, and the aesthetic arrangement on the rock matrix. Specimens with well-formed, radial aggregates are most desirable. ## Popular Localities The only source of specimens is Tolbachik volcano in Kamchatka. Material from this locality is extremely rare and almost exclusively available on the specialized market for systematic and "micromount" minerals.

Care and storage

## Cleaning Due to the extreme rarity and delicacy of specimens, mechanical cleaning is not recommended. If absolutely necessary, compressed air (from a safe distance) can be used to remove loose dust. Avoid contact with water and any chemicals. ## What to Avoid Avoid ultrasonics, steam cleaners, acids, solvents, and sudden temperature changes. The crystals are very small and brittle, susceptible to mechanical damage. ## Storage Genplesite specimens should be stored exclusively in specialized "micromount" boxes, protecting them from dust, shocks, and humidity changes. Avoid direct exposure to sunlight.

External references

Sources

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