| Brianite | |
| Category: | Phosphate minerals |
| Formula: | Na2CaMg(PO4)2 |
| Imasymbol: | Bne[1] |
| Strunz: | 8.AC.30 |
| System: | Monoclinic |
| Class: | Prismatic (2/m) (same H-M symbol) |
| Symmetry: | P21/a |
| Unit Cell: | a = 13.36 Å, b = 5.23 Å, c = 9.13 Å, β = 91.2°; Z = 4 |
| Color: | Colorless |
| Habit: | Anhedral grains with lamellar structure visible under polarized light |
| Twinning: | Polysynthetic on |
| Mohs: | 4-5 |
| Luster: | Vitreous |
| Diaphaneity: | Transparent |
| Gravity: | 3.0-3.1 |
| Opticalprop: | biaxial (-) |
| Refractive: | nα = 1.598, nβ = 1.605, nγ = 1.608 |
| Birefringence: | 0.010 |
| 2V: | 63° to 65° |
| Extinction: | 2 to 3° from lamellae |
| References: | [2] |
Brianite is a phosphate mineral with the chemical formula Na2CaMg(PO4)2.[3] It was first identified in an iron meteorite.[4] This mineral is named after Brian Harold Mason (1917–2009), a pioneer in meteoritics.[4]
It was first reported from the Dayton meteorite in Montgomery County, Ohio in 1966.[4] It occurs in phosphate nodules within the meteorite. Associated minerals include: panethite, whitlockite, albite, enstatite, schreibersite, kamacite, taenite, graphite, sphalerite and troilite.[5]