Grossite

Grossite
General
CategoryOxide minerals
Formula
(repeating unit)
CaAl4O7
IMA symbolGss[1]
Strunz classification4.CC.15
Dana classification07.03.02.01
Crystal systemMonoclinic
Crystal classPrismatic (2/m)
(same H-M symbol)
Space groupC2/c
Unit cella = 12.94, b = 8.91
c = 5.44 [Å]; β = 107.01°; Z = 4
Identification
ColorColorless to white
Crystal habitLathlike or subhedral rounded grains in polycrystalline aggregates rimmed by melilite (in meteorites)
LusterVitreous
StreakWhite
DiaphaneityTransparent
Specific gravity2.88
Optical propertiesBiaxial (+)
Refractive indexnα = 1.618 nβ = 1.618 nγ = 1.652
Birefringenceδ = 0.034
2V angleMeasured: 15°
References[2][3][4]

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.[3][4]

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.[2][4]

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.[2]

  1. ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
  2. ^ a b c Handbook of Mineralogy
  3. ^ a b Mindat.org
  4. ^ a b c Webmineral data