| Brianite | |
|---|---|
 Small white microcrystals of brianite from the Dayton meteorite | |
| General | |
| Category | Phosphate minerals |
| Formula (repeating unit) | Na2CaMg(PO4)2 |
| IMA symbol | Bne[1] |
| Strunz classification | 8.AC.30 |
| Crystal system | Monoclinic |
| Crystal class | Prismatic (2/m) (same H-M symbol) |
| Space group | P21/a |
| Unit cell | a = 13.36 Å, b = 5.23 Å, c = 9.13 Å, β = 91.2°; Z = 4 |
| Identification | |
| Color | Colorless |
| Crystal habit | Anhedral grains with lamellar structur visible under polarized light |
| Twinning | Polysynthetic on {100} |
| Mohs scale hardness | 4-5 |
| Luster | Vitreous |
| Diaphaneity | Transparent |
| Specific gravity | 3.0-3.1 |
| Optical properties | biaxial (-) |
| Refractive index | nα = 1.598, nβ = 1.605, nγ = 1.608 |
| Birefringence | 0.010 |
| 2V angle | 63° to 65° |
| Extinction | 2 to 3° from lamellae |
| References | [2][3][4][5] |
Brianite is a phosphate mineral with the chemical formula Na2CaMg(PO4)2.[4] It was first identified in an iron meteorite.[3] This mineral is named after Brian Harold Mason (1917–2009), a pioneer in meteoritics.[3]
It was first reported from the Dayton meteorite in Montgomery County, Ohio in 1966.[3] It occurs in phosphate nodules within the meteorite. Associated minerals include: panethite, whitlockite, albite, enstatite, schreibersite, kamacite, taenite, graphite, sphalerite and troilite.[5]