Tissintite

Chemical formula: (Ca,Na,◻)AlSi₂O₆

Tissintite is an extremely rare pyroxene, discovered in the Martian meteorite Tissint, distinguished by its extraterrestrial origin.

## Characteristics Tissintite is a mineral from the clinopyroxene group, first identified in 2013. It occurs as microscopic grains, usually ranging from a few to several tens of micrometers in size, within Martian meteorites. Due to its size, its visual features are not visible to the naked eye and require advanced analytical techniques, such as electron microscopy, for observation. ## Physical Properties As a mineral with a pyroxene structure, tissintite is characterized by significant hardness. Its density was calculated based on unit cell parameters and is 3.395 g/cm³. The crystals are too small to determine their luster or transparency in a standard way. ## History and Name The mineral's name comes from the Tissint meteorite, in which it was discovered. This meteorite fell on July 18, 2011, near the town of Tissint in Morocco. Tissintite was officially approved as a new mineral by the International Mineralogical Association (IMA) in 2013. Its discovery is crucial for understanding the geological processes occurring on Mars, including the high pressure and temperature conditions prevailing during meteorite impacts on the planet's surface.

Properties

Density
3.395
Crystal system
Monoclinic

Diagnostic features

## Identification Identification of tissintite is impossible without specialized equipment. It requires the use of advanced techniques, such as transmission electron microscopy (TEM) and electron diffraction, which allow for the analysis of the crystal structure and chemical composition of microscopic grains. ## Distinguishing from Similar Minerals Tissintite is a polymorph of jadeite with a clinopyroxene structure (C2/c). Under laboratory conditions, it is distinguished from other pyroxenes and minerals of similar composition based on the unique parameters of its crystallographic unit cell and characteristic spectra obtained during analyses. ## Crystal Forms This mineral occurs as anhedral (irregularly shaped) grains of microscopic size, often forming lamellar intergrowths with other mineral phases within impact glass (maskelynite).

Geological environment

## Genesis Tissintite is a high-pressure mineral. It forms under extreme pressure (above 20 GPa) and temperature conditions that accompany the impacts of large objects on a planetary surface. In the case of known occurrences, it formed as a result of shock metamorphism of Martian basaltic rocks during an impact that ejected them into space. ## Mineral Associations In the Tissint meteorite, tissintite co-occurs with other minerals typical of Martian shergottites, such as pyroxenes (pigeonite, augite), olivine, plagioclase (transformed into maskelynite), as well as other high-pressure minerals like ringwoodite and ahrensite. ## Locations The only confirmed occurrence of tissintite is in the Martian meteorite Tissint, found in the Tata province of Morocco. Its presence has also been identified in another Martian meteorite, NWA 8159.

Rarity

Extremely rare

For collectors

## Quality Criteria Tissintite does not occur as standalone collector's specimens. Its value is purely scientific and inextricably linked to the value of the meteorite in which it is found. For meteorite collectors, specimens with confirmed presence of rare minerals, such as tissintite, are highly sought after, and their value depends on the mass, provenance, and degree of studied material. ## Popular Localities The only "locality" in a collector's context is the Tissint meteorite fall area in Morocco. Fragments of this meteorite are found in institutional and private collections worldwide.

Care and storage

## Cleaning Specimens containing tissintite (meteorites) are extremely valuable and sensitive. They should not be cleaned independently. All conservation treatments should be carried out exclusively by specialized laboratories dealing with the preparation of extraterrestrial material. ## What to Avoid Absolutely everything should be avoided: water, chemicals, ultrasonics, changes in temperature and humidity. Contact with the Earth's atmosphere, especially with moisture, can lead to irreversible chemical changes and degradation of the mineral and the entire specimen. ## Storage Storage requires museum or laboratory conditions. It is best to store specimens in hermetic containers with a controlled, inert atmosphere (e.g., in nitrogen or argon) and stable, low humidity. They should be protected from light, shocks, and contaminants.

External references

Sources

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