Elgoresyite

Chemical formula: (Mg<sub>5</sub>Si<sub>2</sub>)O<sub>9</sub>

Elgoresyite is a newly discovered mineral from the magnesium silicate group, identified in the Suizhou meteorite, distinguished by its unique crystal structure.

## Characteristics Elgoresyite is a silicate group mineral officially recognized by the International Mineralogical Association (IMA) in 2022. It occurs as microscopic, anhedral (lacking crystal faces) grains, typically not exceeding 100 micrometers in size. It is one of the components of shock-metamorphosed veins in the Suizhou chondrite meteorite. Its identification requires advanced analytical techniques such as electron diffraction and spectroscopy. ## Physical Properties Due to the microscopic size of the grains, most physical properties, such as hardness, density, luster, or transparency, have not yet been determined by macroscopic methods. The calculated density of the mineral is 3.43 g/cm³. It is optically uniaxial with a negative optical sign. ## Colors and Varieties The observed elgoresyite grains are colorless. No varieties of this mineral have been distinguished. ## History and Name The mineral is named in honor of Ahmed El Goresy (born 1934), a distinguished German scientist specializing in meteorite and high-pressure mineral research. It was discovered and described by an international team of researchers led by Chi Ma. The type locality (locus typicus) is the Suizhou meteorite, which fell in 1986 in Hubei Province, China. ## Applications Elgoresyite has no commercial or industrial applications. Its significance is purely scientific, as it provides information about processes occurring under extremely high pressure and temperature conditions, such as those found during cosmic impacts.

Properties

Streak
White
Density
3.43
Transparency
Transparent
Crystal system
Hexagonal

Diagnostic features

## Identification Identification of elgoresyite is impossible without specialized laboratory equipment. It requires the use of techniques such as scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS) for chemical composition analysis, and precession electron diffraction (PED) or electron backscatter diffraction (EBSD) to determine the crystal structure. ## Distinguishing from Similar Minerals At the microscopic level, elgoresyite must be distinguished from other high-pressure magnesium silicates, such as ringwoodite, wadsleyite, or bridgmanite. The key is a combination of precise chemical composition analysis (Mg:Si ratio) and its unique hexagonal crystal structure, which differentiates it from orthorhombic or cubic polymorphs. ## Crystal Forms This mineral forms exclusively microscopic, anhedral grains within shock veins in the meteorite. No well-formed (euhedral) crystals have been observed.

Geological environment

## Genesis Elgoresyite is a high-pressure mineral that forms under extreme conditions of pressure (estimated at 17-25 GPa) and temperature (2000-2300 °C). Such conditions are the result of shock metamorphism caused by the impact of a celestial body. In the case of the type locality, the mineral crystallized from an impact melt in shock veins cutting through the chondrite meteorite. ## Mineral Associations Elgoresyite co-occurs with other high-pressure minerals in the Suizhou meteorite. Its direct associations include ringwoodite, majorite, lingunite, magnesiowüstite, and magnesium- and iron-rich silicate glass. ## Localities The only confirmed occurrence of elgoresyite in the world is the Suizhou meteorite, found in Suixian County, Hubei Province, China.

Rarity

Extremely rare

For collectors

## Quality Criteria Elgoresyite, as a mineral occurring exclusively as microscopic inclusions, is not an object of collector trade. Its value is purely scientific. For research institutions and museums, fragments of the Suizhou meteorite containing analytically confirmed shock veins with this mineral are valuable. ## Market Prices There is no market for this mineral. The prices of Suizhou meteorite fragments depend on their mass and provenance, not on the presence of microscopic elgoresyite. ## Popular Localities The only locality is the Suizhou meteorite, fragments of which are found in institutional and private collections worldwide.

Care and storage

## Cleaning Due to its occurrence exclusively as microscopic inclusions in meteorites, individual specimens are not available and do not require cleaning. ## What to Avoid Meteorite specimens containing elgoresyite should be protected from moisture, chemicals, and extreme temperature changes to preserve the integrity of the entire find. ## Storage Storing meteorite fragments containing this mineral requires museum conditions, preferably in a dry environment, in specialized containers that protect against contamination and mechanical damage.

External references

Sources

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