Davisite
Chemical formula: CaScAlSiO<sub>6</sub>
An extremely rare scandium pyroxene, found exclusively in meteorites, crucial for studying the early history of the Solar System.
Properties
- Mohs hardness
- 6
- Luster
- Vitreous
- Streak
- White
- Density
- 3.43
- Cleavage
- Good on {110}
- Fracture
- Uneven
- Transparency
- Transparent to translucent
- Crystal system
- Monoclinic
Diagnostic features
## Identification Identification of davisite is impossible without advanced analytical techniques. Due to the microscopic size of the grains, identification relies on chemical analysis using an electron microprobe (EMPA) or Raman spectroscopy. A key diagnostic feature is the high scandium content in the pyroxene structure. ## Differentiation from Similar Minerals Davisite can be confused with other pyroxenes co-occurring in CAIs, such as diopside or fassaite (a variety of augite). The only way to differentiate them is through precise chemical analysis, which will reveal the presence of scandium in quantities defining davisite. ## Crystal Forms It typically forms anhedral (lacking well-formed faces) or subhedral (partially formed) grains ranging in size from a few to several tens of micrometers. Rarely, small, poorly developed prismatic crystals are observed.
Geological environment
## Genesis Davisite is a high-temperature mineral that crystallized directly from gas in the primordial solar nebula at temperatures exceeding 1200°C. Its formation is associated with the oldest solid matter in our Solar System. It occurs exclusively in calcium-aluminum-rich inclusions (CAIs - Calcium-Aluminum-rich Inclusions) in carbonaceous chondrites. ## Mineral Associations Minerals co-occurring with davisite in CAIs include other high-temperature minerals such as spinel, melilite (gehlenite, åkermanite), perovskite, hibonite, and diopside. ## Localities The only confirmed occurrences of davisite are in meteorites. The type locality is the Allende meteorite, which fell in Chihuahua, Mexico. Its presence has also been reported in other carbonaceous chondrites, including Vigarano (Italy, fell in 1910) and Efremovka (Kazakhstan).
Rarity
Extremely rare
For collectors
## Quality Criteria Davisite is not a collector's mineral in the traditional sense. It does not form macroscopic specimens. Its value is purely scientific and is inextricably linked to the value of the meteorite in which it is found. For research institutions and specialized meteorite collectors, the presence of well-characterized davisite in a CAI inclusion significantly increases the scientific value of the specimen. ## Market Prices There is no market for davisite as a separate mineral. Prices apply to meteorite fragments in which it may occur. The value of such a fragment depends on its size, meteorite type, provenance, and the presence of scientifically interesting inclusions. ## Popular Localities The most known and valued source of davisite is fragments of the Allende meteorite. Specimens from other carbonaceous chondrites containing this mineral are also highly valued in scientific circles.
Care and storage
## Cleaning Davisite specimens are microscopic grains within the host rock (meteorite), so they are not cleaned directly. If it is necessary to clean a meteorite fragment containing davisite, only compressed air or a very soft brush should be used to remove dust. All liquids should be avoided. ## What to Avoid Contact with water, chemicals, acids, and solvents must be strictly avoided. The meteorite material in which davisite occurs can be porous and sensitive to moisture. It should be protected from temperature fluctuations, vibrations, and mechanical damage. ## Storage Meteorite fragments with davisite should be stored in stable, dry conditions, preferably in sealed containers (e.g., membrane boxes or with a desiccant), to prevent degradation and contamination. Microscopic preparations (thin sections) require storage in special boxes, protected from dust and damage.