Brezinaite
Chemical formula: Cr<sup>2+</sup>Cr<sup>3+</sup><sub>2</sub>S<sup>2-</sup><sub>4</sub>
Brezinaite is a rare chromium sulfide found mainly in iron meteorites, forming small, tabular crystals with a metallic luster.
Properties
- Mohs hardness
- 4
- Luster
- Metallic
- Streak
- Black
- Density
- 4.13
- Cleavage
- None
- Fracture
- Uneven
- Transparency
- Opaque
- Crystal system
- Trigonal
Diagnostic features
## Identification Identifying brezinaite is extremely difficult without advanced analytical methods. Preliminary identification is based on its occurrence in a characteristic environment – as black, metallic, hexagonal flakes within iron meteorites. Definitive identification requires methods such as electron microscopy with EDS analysis or X-ray diffraction (XRD). ## Distinguishing from Similar Minerals It can be confused with other opaque accessory minerals in meteorites, such as graphite, chromite, or other sulfides (e.g., troilite). Brezinaite is distinguished by its chemical composition (dominance of chromium and sulfur) and its characteristic hexagonal crystal morphology, visible under high magnification. ## Crystal Forms It forms very small, thin, tabular crystals with a hexagonal outline. They typically occur as single, isolated flakes or small aggregates embedded in the surrounding metallic matrix (kamacite) or other minerals, such as schreibersite.
Geological environment
## Genesis Brezinaite is a mineral of extraterrestrial origin. It forms under strongly reducing conditions within the parent bodies of asteroids from which iron meteorites originate. It crystallizes during the very slow cooling of an iron-nickel melt in the presence of sulfur and chromium. ## Mineral Associations It most often co-occurs with minerals typical of iron meteorites, such as kamacite, taenite (iron-nickel alloys), schreibersite (iron-nickel phosphide), and daubréelite (another chromium sulfide). Graphite and chromite may also accompany it. ## Localities Brezinaite is known exclusively from meteorites. Besides its type locality in the Tucson meteorite (Arizona, USA), its presence has been confirmed in other iron meteorites, including the Udei Station meteorite (Nigeria), the Hex River Mountains meteorite (South Africa), and in samples from Meteor Crater (Canyon Diablo, Arizona, USA).
Rarity
Extremely rare
For collectors
## Quality Criteria The quality of a brezinaite specimen is almost exclusively determined by the quality of the meteorite matrix itself and the visibility and size of the inclusions. The most desirable specimens are those in which brezinaite crystals, despite their microscopic size, are well-formed, visible without the need for very high magnification, and embedded in an aesthetically pleasing matrix. Every confirmed specimen is a valuable scientific and collectible acquisition. ## Popular Localities The most known and historical source of brezinaite is the Tucson meteorite. Specimens from this meteorite are classics and serve as a reference point for this mineral.
Care and storage
## Cleaning Due to its extreme rarity and small crystal size, brezinaite specimens embedded in a meteoritic matrix are generally not subjected to cleaning. Any mechanical or chemical intervention risks irreversible damage or loss of the mineral. If dusty, compressed air can be used from a safe distance. ## What to Avoid Avoid contact with all chemicals, acids, and bases. The mineral is sensitive to oxidation, so it should be protected from moisture and sudden temperature changes. It should not be subjected to ultrasonic cleaning. ## Storage Specimens containing brezinaite should be stored under stable conditions, preferably in sealed, dry containers (e.g., with a desiccant) to minimize the risk of oxidation. They should be protected from dust and mechanical damage.