Brianite

Brianite is a phosphate mineral with the chemical formula Na2CaMg(PO4)2.[3] It was first identified in an iron meteorite.[2] This mineral is named after Brian Harold Mason (1917–2009), a pioneer in meteoritics.[2]

Brianite
General
CategoryPhosphate minerals
Formula
(repeating unit)
Na2CaMg(PO4)2
Strunz classification8.AC.30
Crystal systemMonoclinic
Crystal classPrismatic (2/m)
(same H-M symbol)
Space groupP21/a
Unit cella = 13.36 Å, b = 5.23 Å,
c = 9.13 Å, β = 91.2°; Z = 4
Identification
ColorColorless
Crystal habitAnhedral grains with lamellar structur visible under polarized light
TwinningPolysynthetic on {100}
Mohs scale hardness4-5
LusterVitreous
DiaphaneityTransparent
Specific gravity3.0-3.1
Optical propertiesbiaxial (-)
Refractive indexnα = 1.598, nβ = 1.605, nγ = 1.608
Birefringence0.010
2V angle63° to 65°
Extinction2 to 3° from lamellae
References[1][2][3][4]

It was first reported from the Dayton meteorite in Montgomery County, Ohio in 1966.[2] It occurs in phosphate nodules within the meteorite. Associated minerals include: panethite, whitlockite, albite, enstatite, schreibersite, kamacite, taenite, graphite, sphalerite and troilite.[4]

See also

References


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