Breyite
Chemical formula: Ca<sub>3</sub>Si<sub>3</sub>O<sub>9</sub>
Breyite is a high-pressure calcium silicate, a key component of some diamonds and Earth's mantle rocks.
Properties
- Luster
- Adamantine
- Density
- 4.27
- Transparency
- Transparent
- Crystal system
- Cubic
Diagnostic features
## Identification Identification of breyite is possible only through advanced analytical techniques, such as X-ray diffraction (XRD), electron microscopy (SEM/TEM), and Raman spectroscopy, performed on microscopic inclusions within host minerals, most often diamonds. Visual identification is not possible. ## Distinguishing from Similar Minerals At the analytical level, breyite (cubic CaSiO₃) is distinguished from its polymorphs – wollastonite and pseudowollastonite (crystallizing in monoclinic and triclinic systems) – based on its distinct crystal structure detected by diffraction methods. ## Crystal Forms It is observed as submicron, most often rounded or irregular grains and aggregates within diamonds.
Geological environment
## Genesis Breyite is a high-pressure mineral, crystallizing under conditions prevailing in the Earth's lower mantle, at depths exceeding 300 km. It forms in ultramafic rocks, such as peridotites and eclogites. Its presence in diamonds is evidence of their ultra-high-pressure origin. On the Earth's surface, it is unstable and transforms into low-pressure polymorphs, such as wollastonite. ## Mineral Associations Most often, it co-occurs with diamond (as an inclusion). Other associated minerals, found as co-occurring inclusions, include enstatite, ferropericlase, walstromite, and other high-pressure silicate and oxide phases. ## Localities As inclusions in diamonds, it has been identified in material from the Orapa mine in Botswana and the Cullinan (formerly Premier) mine in South Africa. It has also been found in the Suizhou meteorite (L6 chondrite).
Rarity
Extremely rare
For collectors
## Quality Criteria Breyite is not an object of collector interest. Its value is purely scientific. Diamond specimens containing confirmed breyite inclusions are extremely valuable for research institutions, but their market value is determined by the quality of the diamond itself, not the presence of inclusions. ## Popular Localities The only confirmed localities are the Orapa (Botswana) and Cullinan (South Africa) diamond mines, from which research samples originate.
Care and storage
## Cleaning Not applicable. The mineral occurs exclusively as microscopic inclusions in other minerals, primarily diamonds. ## What to Avoid Not applicable. Breyite is unstable under the pressure and temperature conditions prevailing on the Earth's surface and undergoes retrogradation to other mineral phases. ## Storage Not applicable. Specimens containing breyite (mainly diamonds) are stored according to the standards for the host mineral.