Grossite

Grossite
General
Category	Oxide minerals
Formula (repeating unit)	CaAl4O7
Strunz classification	4.CC.15
Dana classification	07.03.02.01
Crystal system	Monoclinic
Crystal class	Prismatic (2/m) (same H-M symbol)
Space group	C2/c
Unit cell	a = 12.94, b = 8.91 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)
|re|er}}	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]

See also

• Glossary of meteoritics

References

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