Tuite
Chemical formula: Ca<sub>3</sub>(PO<sub>4</sub>)<sub>2</sub>
Tuite is an extremely rare mineral, a high-pressure polymorph of calcium phosphate, found mainly in meteorites and diamonds.
Properties
- Mohs hardness
- 5
- Luster
- Vitreous
- Streak
- White
- Density
- 3.12
- Cleavage
- None
- Transparency
- Transparent
- Crystal system
- Trigonal
Diagnostic features
## Identification Identification of tuite is impossible with the naked eye and requires advanced analytical techniques. Its environment of occurrence is key – shock veins in meteorites or inclusions in superdeep diamonds. Confirmation of identity is obtained using Raman spectroscopy, X-ray diffraction (XRD), or electron microprobe analysis (EMPA). ## Distinguishing from Similar Minerals Tuite is most often confused with its polymorphs – whitlockite and merrillite, which have an identical chemical composition but a different crystal structure. Differentiation is possible only by instrumental methods. From other colorless minerals (e.g., quartz, forsterite) in the same environment, it is distinguished by optical and structural properties, which can only be studied in a laboratory. ## Crystal Forms This mineral primarily forms anhedral (irregular, without developed faces) or subhedral (partially developed) grains and aggregates. It usually occurs as single, isolated crystals of microscopic size.
Geological environment
## Genesis Tuite is a high-pressure mineral. It forms in at least two environments. The first is shock metamorphism processes, occurring during a meteorite impact with another celestial body, leading to extremely high pressures and temperatures. The second is crystallization under conditions of the Earth's upper mantle, at depths of hundreds of kilometers, from where the mineral is transported to the surface as an inclusion in diamonds. ## Mineral Associations In meteorites, tuite coexists with other high-pressure minerals such as ringwoodite, wadsleyite, majorite, as well as iron-nickel minerals like taenite and kamacite. In diamonds, its associated minerals are mainly forsterite and enstatite. ## Localities The most important and confirmed localities for this mineral are: - Suizhou meteorite (L6 chondrite) in Hubei Province, China (type locality). - Diamonds from the São Luiz River region (Juina) in Mato Grosso state, Brazil. - Tenham meteorite (L6 chondrite), which fell in Queensland, Australia.
Rarity
Extremely rare
For collectors
## Quality Criteria The collector's value of tuite is inextricably linked to its scientific significance. The most important criterion is the unequivocal confirmation of the mineral's identity using analytical methods. Specimens in which the tuite inclusion is relatively large (for this mineral), clearly visible, and photographically documented are valued. Additional value is provided by the coexistence with other rare high-pressure minerals in the same sample. ## Popular Localities The most known and valued specimens come from two main sources: fragments of the Suizhou meteorite and diamonds (both rough and cut) from the Juina area in Brazil. Samples from these localities are the standard for this mineral.
Care and storage
## Cleaning Due to its occurrence as microscopic inclusions, cleaning individual specimens is usually impossible and unnecessary. When working with isolated grains, avoid all liquids and chemicals. A gentle air blower (photographic bulb) can be used to remove dust. ## What to Avoid As a phosphate, tuite may be sensitive to strong acids. Extreme temperatures and ultrasonication should be avoided, as they could damage delicate inclusions or the surrounding material. ## Storage Specimens containing tuite (most often as polished meteorite thin sections or in diamonds) should be stored in stable conditions, away from dust and moisture. The safest way is to store them in specialized "micromount" boxes or in padded display cases, protecting them from shocks and mechanical damage.