Liuite
Chemical formula: Fe<sup>2+</sup>Ti<sup>4+</sup>O<sub>3</sub>
Liuite is a high-pressure, orthorhombic polymorph of ilmenite, discovered as microscopic inclusions in the Martian meteorite Shergotty.
Description
## Characteristics Liuite is a high-pressure, orthorhombic polymorphic variety of ilmenite (FeTiO₃). It does not form macroscopic crystals, and its occurrence is limited to microscopic, often nanometer-sized, lamellae or grains within other minerals, mainly titanomagnetite. For this reason, it is impossible to identify visually without advanced analytical techniques. Its significance is purely scientific, providing data on processes occurring under extreme pressure conditions, e.g., during meteorite impacts. ## Physical Properties Most of the physical properties of liuite are unknown due to the microscopic size of its occurrences. It is an opaque mineral. Its density, calculated based on unit cell parameters, is approximately 5.06 g/cm³, which is higher than that of ilmenite. Hardness, cleavage, and fracture have not been determined. ## Colors and Varieties Due to the microscopic nature of its occurrences, color is not a diagnostic feature. In microscopic studies under reflected light, its optical properties are similar to ilmenite. No varieties are distinguished. ## History and Name The mineral was officially recognized by the IMA in 2010. Its name commemorates Lin-gun Liu (1943–2009), a Taiwanese geophysicist and pioneer in the field of experimental high-pressure petrology. Liuite was discovered in the Shergotty meteorite – a famous Martian shergottite that fell in India in 1865. The identification of the mineral was only possible many years later through the use of modern research methods. ## Applications Liuite has no commercial or industrial applications. It is an object of scientific interest as an indicator of shock conditions (extreme pressure and temperature) prevailing during cosmic impacts and processes occurring in planetary interiors.
Diagnostic features
## Identification Identification of liuite is impossible without specialized equipment. It requires the use of advanced techniques, such as electron backscatter diffraction (EBSD) or synchrotron X-ray diffraction, which allow for the determination of its orthorhombic crystal structure. It occurs as microscopic lamellae or grains within titanomagnetite. ## Distinguishing from Similar Minerals The most important mineral to distinguish it from is ilmenite, of which liuite is a polymorph. The difference lies in the crystallographic system: liuite crystallizes in the orthorhombic system, while ilmenite crystallizes in the trigonal system. This difference is a result of liuite forming under much higher pressure conditions. It can only be distinguished from other iron and titanium oxides in meteorites by structural and chemical analysis. ## Crystal Forms It does not form visible crystals. It occurs exclusively in the form of microscopic, elongated aggregates (lamellae) or irregular grains crystallographically oriented within the parent mineral.
Geological environment
## Genesis Liuite is a high-pressure mineral, formed as a result of shock metamorphism. It forms due to the phase transformation of ilmenite under extremely high pressure (above 12 GPa) and temperature, generated during the impact of a hypervelocity celestial body. ## Mineral Associations This mineral occurs in close association with titanomagnetite, in which it forms microscopic inclusions. It co-occurs with other minerals typical of shocked Martian meteorites, such as maskelynite (diaplectic glass formed from plagioclase), pyroxenes, and other high-pressure phases. ## Localities The only confirmed locality of liuite in the world is the Shergotty meteorite, which fell in 1865 near the town of Sherghati in the state of Bihar, India. This is therefore the type locality of this mineral.
Rarity
Extremely rare
Collector aspects
## Quality Criteria Liuite as a mineral is not an object of collecting due to its microscopic nature. Collectors and scientific institutions seek fragments of the Shergotty meteorite itself. The value of these specimens depends on their mass, provenance, and scientific value, not on the presence of observable liuite. ## Popular Localities Specimens of the Shergotty meteorite in which liuite has been identified are extremely rare on the collector's market. The vast majority of the material is in institutional and museum collections, such as the Natural History Museum in London or the National Museum of Natural History in Washington.
Care and storage
## Cleaning Specimens containing liuite (i.e., fragments of the Shergotty meteorite) should generally not be cleaned. Any attempt at mechanical or chemical cleaning could irrevocably destroy the microscopic occurrences of the mineral and damage the delicate structure of the meteorite itself. ## What to Avoid Contact with chemicals, water, and high humidity, which can lead to the oxidation of metallic phases in the meteorite, should be avoided. Sudden temperature changes, vibrations, and direct sunlight are also not recommended. ## Storage Fragments of the meteorite containing liuite should be stored under stable conditions, preferably in specialized collector's boxes with a desiccant. Display should be in sealed display cases, away from sources of heat and light.