| Grossite | |
| Category: | Oxide minerals |
| Formula: | CaAl4O7 |
| Imasymbol: | Gss[1] |
| Strunz: | 4.CC.15 |
| Dana: | 07.03.02.01 |
| System: | Monoclinic |
| Class: | Prismatic (2/m) (same H-M symbol) |
| Symmetry: | C2/c |
| Unit Cell: | a = 12.94, b = 8.91 c = 5.44 [Å]; β = 107.01°; Z = 4 |
| Color: | Colorless to white |
| Habit: | Lathlike or subhedral rounded grains in polycrystalline aggregates rimmed by melilite (in meteorites) |
| Luster: | Vitreous |
| Streak: | White |
| Diaphaneity: | Transparent |
| Gravity: | 2.88 |
| Opticalprop: | Biaxial (+) |
| Refractive: | nα = 1.618 nβ = 1.618 nγ = 1.652 |
| Birefringence: | δ = 0.034 |
| 2V: | Measured: 15° |
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.[4] [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.[4]