Grossite

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Grossite
General
Category Oxide minerals
Formula
(repeating unit)
CaAl4O7
Strunz classification 04.CC.15
Dana classification 07.03.02.01
Crystal symmetry Monoclinic (2/m) prismatic
Unit cell a = 12.94 Å, b = 8.91 Å, c = 5.44 Å; β = 107.01°; Z = 4
Identification
Color Colorless to white
Crystal habit Lathlike or subhedral rounded grains in polycrystalline aggregates rimmed by melilite (in meteorites)
Crystal system Monoclinic
Luster Vitreous
Streak White
Diaphaneity Transparent
Specific gravity 2.88
Optical properties Biaxial (+)
Refractive index nα = 1.618 nβ = 1.618 nγ = 1.652
Birefringence δ = 0.034
2V angle Measured: 15°
References [1][2][3]

Grossite is a calcium aluminium oxide mineral with formula CaAl4O7. It is a colorless to white vitreous mineral which crystallizes in the monoclinic crystal system.[2][3]

Grossite was first described 1994 for an occurrence in the Hatrurim Formation of Israel. It was named for Shulamit Gross (1923–2012) of the Geological Survey of Israel.[1][3]

It occurs within high temperature metamorphosed impure limestone of the Hatrurim Formation and also within calcium-aluminium rich inclusions in chondritic meteorites. Associated minerals in the Hatrurium include brownmillerite, mayenite and larnite. In meteorites it occurs with perovskite, melilite, hibonite, spinel and calcium rich pyroxene.[1]

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