Marialite | |
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General | |
Category | Tectosilicate |
Formula (repeating unit) | Na4Al3Si9O24Cl |
IMA symbol | Mar[1] |
Strunz classification | 9.FB.15 |
Crystal system | Tetragonal |
Crystal class | Dipyramidal (4/m) (same H-M symbol) |
Space group | I4/m |
Unit cell | a = 12.06 Å, c = 7.572(3) Å; Z = 2 |
Identification | |
Color | Colorless, white, grey; pink, violet, blue, yellow, brown, orange-brown, pale green or reddish |
Crystal habit | Typically flat, pyramidal striated crystals; massive, granular |
Cleavage | Distinct on {100} and {110} |
Fracture | Uneven to conchoidal |
Tenacity | Brittle |
Mohs scale hardness | 5+1⁄2–6 |
Luster | Vitreous, pearly, resinous |
Streak | White |
Diaphaneity | Transparent to opaque |
Specific gravity | 2.55–2.74 |
Density | 2.5–2.62 g/cm3 |
Optical properties | Uniaxial (−) |
Refractive index | nω = 1.539–1.550 nε = 1.532–1.541 |
Birefringence | δ = 0.007 – 0.009 |
References | [2][3][4][5][6] |
Marialite is a silicate mineral with a chemical formula of Na4Al3Si9O24Cl[5][6] if a pure endmember or Na4(AlSi3O8)3(Cl2,CO3,SO4) with increasing meionite content.[3] Marialite is a member of the scapolite group and a solid solution exists between marialite and meionite, the calcium endmember.[3] It is a rare mineral usually used as a collector's stone.