Pyroxferroite
Pyroxferroite (Fe2+,Ca)SiO3 is a single chain inosilicate. It is mostly composed of iron, silicon and oxygen, with smaller fractions of calcium and several other metals. Together with armalcolite and tranquillityite, it is one of the three minerals which were discovered on the Moon during the 1969 Apollo 11 mission. It was then found in Lunar and Martian meteorites as well as a mineral in the Earth's crust. Pyroxferroite can also be produced by annealing synthetic clinopyroxene at high pressures and temperatures. The mineral is metastable and gradually decomposes at ambient conditions, but this process can take billions of years.
| Pyroxferroite | |
|---|---|
Pyroxferroite | |
| General | |
| Category | Inosilicate |
| Formula (repeating unit) | (Fe2+,Ca)SiO3 |
| IMA symbol | Pxf |
| Strunz classification | 9.DO.05 |
| Crystal system | Triclinic |
| Space group | P1 (no. 2) |
| Unit cell | a = 6.6213 Å, b = 7.5506 Å, c = 17.3806 Å, α = 114.267°, β = 82.684°, γ = 94.756°, Z = 14 |
| Identification | |
| Color | Yellow |
| Cleavage | Good on (010), poor on (001) |
| Mohs scale hardness | 4.5–5.5 |
| Luster | Vitreous |
| Streak | White |
| Specific gravity | 3.68–3.76 g/cm3 (measured) |
| Optical properties | Biaxial (+) |
| Refractive index | nα = 1.748–1.756 nβ = 1.750–1.758 nγ = 1.767–1.768 |
| Pleochroism | Faint; pale yellow to yellow-orange |
| 2V angle | 34–40° |
| References | |
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