Wassonite

Chemical formula: Ti²⁺S²⁻

Wassonite is an extremely rare mineral, a titanium sulfide, identified exclusively in the Yamato 691 chondrite meteorite.

## Characteristics Wassonite is a microscopic mineral, invisible to the naked eye. Its grains, identified in the Yamato 691 enstatite meteorite, measured no more than 50x450 nanometers. Due to the extremely small size of the crystals, its visual characteristics, such as the appearance of a typical macroscopic specimen, are unknown. ## Physical Properties Due to the microscopic size of the grains, most physical properties of wassonite, such as hardness, density, luster, or transparency, have not been experimentally determined. The calculated density is 4.62 g/cm³. This mineral crystallizes in the trigonal system, in the same structure as pyrrhotite. ## History and Name The mineral is named in honor of John T. Wasson (born 1940), a professor at the University of California, Los Angeles (UCLA), for his outstanding contributions to meteorite and actinolite research. The mineral was officially approved by the International Mineralogical Association (IMA) in 2010, and its discovery was announced in 2011. It was identified by a team of NASA scientists led by Keiko Nakamura-Messenger in a sample from the Yamato 691 meteorite, found in Antarctica in 1969. ## Applications Currently, wassonite has no industrial applications. Its significance is purely scientific, providing information about the conditions in the early Solar System in which minerals formed.

Properties

Color: Dark bronze to brown
Density: 4.452
Crystal system: Trigonal

Diagnostic features

## Identification Identification of wassonite is impossible without advanced analytical techniques. It requires the use of a transmission electron microscope (TEM) to locate nanometric crystals and chemical composition analysis using energy-dispersive spectroscopy (EDS) to confirm its composition (titanium sulfide). ## Differentiation from Similar Minerals Wassonit coexists with other sulfides, such as troilite (FeS). Differentiating it from these minerals based on visual characteristics is impossible. The only method is precise micro-scale chemical analysis. ## Crystal Forms Observed wassonite crystals appear as nanometric, elongated grains, often with visible structural defects such as dislocations. It does not form macroscopically visible shapes.

Geological environment

## Genesis Wassonit formed as a result of processes occurring in the solar nebula during the initial stage of the Solar System's formation. It crystallized in an environment with very low oxygen partial pressure (strongly reducing) and high temperature, within the parent body (asteroid) from which the Yamato 691 meteorite originated. ## Mineral Associations Wassonit has been found in association with other minerals typical of enstatite chondrites, such as enstatite, troilite, sinoite, and various silicate and metallic phases (kamacite). ## Localities The only confirmed locality of wassonite in the world is the Yamato 691 meteorite, found in the Yamato Mountains in Antarctica. This is its type locality.

Rarity

Extremely rare

For collectors

## Quality Criteria Wassonit is not a collector's mineral in the traditional sense. It does not form specimens that can be collected or displayed. Its value is purely scientific, and the only material in which it can be found are fragments of the Yamato 691 meteorite, stored in the collections of research institutions such as NASA and the National Institute of Polar Research in Japan.

Care and storage

## Cleaning Specimens containing wassonite (meteorite fragments) should not be cleaned using wet methods, especially with chemicals, due to the risk of damaging the microscopic grains and associated minerals. ## What to Avoid Wassonite is unstable under terrestrial conditions and readily oxidizes upon contact with air and moisture. Avoid temperature changes, humidity, and exposure to atmospheric oxygen, which can lead to its decomposition. ## Storage Materials containing wassonite, which are subjects of scientific research, should be stored under specialized conditions, preferably in an oxygen-free atmosphere (e.g., in nitrogen chambers) or in a vacuum, to prevent degradation. Storage in a dry desiccator is an absolute minimum.