Stöfflerite

Chemical formula: CaAl₂Si₂O₈

Stöfflerite is a high-pressure, tetragonal variety of anorthite, occurring as microscopic grains in Martian meteorites.

## Characteristics Stöfflerite is a mineral from the tectosilicate group, representing a high-pressure polymorph of anorthite. It occurs as very fine, colorless, transparent grains, which can only be observed under a microscope in thin sections of rocks. Its identification requires advanced analytical techniques, such as electron diffraction. ## Physical Properties As a mineral observed exclusively in the form of microscopic inclusions, most of its physical properties, such as hardness, luster, or density, have not been directly measured on macroscopic samples. It is known to be transparent. ## Colors and Varieties Observed stöfflerite crystals are colorless. No varieties are distinguished. ## History and Name The mineral is named in honor of Dieter Stöffler (born 1939), a German mineralogist and planetologist from the Museum of Natural History in Berlin, for his fundamental contributions to the study of impact processes and meteorites. The mineral was approved by the IMA in 2014 (IMA2014-097). ## Uses Stöfflerite has no industrial application. Its significance is purely scientific, as an indicator of the extremely high pressure and temperature conditions that prevailed during meteorite impacts.

Properties

Transparency
Transparent
Crystal system
Tetragonal

Diagnostic features

## Identification Identification of stöfflerite is impossible without specialized equipment. It requires microscopic analysis of meteorite thin sections and the use of methods such as transmission electron microscopy (TEM) to determine its tetragonal crystal structure. ## Distinguishing from Similar Minerals Stöfflerite is a polymorph of anorthite. Distinguishing it from anorthite and other plagioclase feldspars relies solely on crystal structure analysis. Visually, in the form of microscopic grains, it is indistinguishable from many other colorless rock-forming minerals. ## Crystal Forms The mineral forms microscopic, tabular crystals up to 50 micrometers in size, often arranged in lamellar or fan-like aggregates.

Geological environment

## Genesis Stöfflerite forms as a result of shock metamorphism, i.e., rapid transformations under extremely high pressure (above 30 GPa) and temperature, which accompany impacts of celestial bodies. It forms in shock veins within plagioclase-rich rocks, such as shergottites. ## Mineral Associations This mineral co-occurs with other high-pressure minerals and products of shock metamorphism. Its typical associations include maskelynite (diaplectic plagioclase glass), ringwoodite, majorite, as well as olivines and pyroxenes. ## Localities Its occurrence has been confirmed exclusively in Martian meteorites (shergottites). It was discovered in the Northwest Africa 856 (NWA 856) meteorite, and subsequently identified in others, such as Tissint and Zagami.

Rarity

Extremely rare

For collectors

## Quality Criteria Stöfflerite is not traded as a separate mineral for collectors. Its value is inextricably linked to the scientific and market value of the meteorite in which it is found. For scientific institutions and advanced meteorite collectors, the presence of confirmed stöfflerite significantly increases the value of the specimen as evidence of shock processes. ## Popular Localities The most important "localities" are the meteorites in which it was found, primarily shergottites from Northwest Africa (e.g., NWA 856) and historical falls, such as Zagami (Nigeria) and Tissint (Morocco).

Care and storage

## Cleaning Not applicable. The mineral occurs exclusively as microscopic inclusions within meteorite rocks and is not extracted as separate specimens. ## What to Avoid Not applicable. ## Storage Meteorite specimens containing stöfflerite should be stored under stable conditions, away from moisture and contaminants, to protect the entire rock sample.

External references

Sources

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