Scawtite
Scawtite is a hydrous calcium silicate mineral with carbonate, formula: Ca7(Si3O9)2CO3·2H2O. It crystallizes in the monoclinic crystal system as thin plates or flat prisms.[2]
Scawtite | |
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General | |
Category | Silicate mineral |
Formula (repeating unit) | Ca7(Si3O9)2CO3·2H2O |
Strunz classification | 9.CK.15 |
Dana classification | 64.2.1.1 |
Crystal system | Monoclinic |
Crystal class | Prismatic (2/m) (same H-M symbol) |
Space group | C2/m |
Unit cell | a = 10.12 Å, b = 15.18 Å c = 6.62 Å; β = 100.55°; Z = 2 |
Identification | |
Color | Colorless |
Crystal habit | Platy - micaceous, parallel to radiating clusters |
Cleavage | Perfect on {001}, poor on {010} |
Mohs scale hardness | 4–5 |
Luster | Vitreous |
Diaphaneity | Transparent |
Specific gravity | 2.77 |
Optical properties | Biaxial (+) |
Refractive index | nα = 1.597 - 1.603 nβ = 1.606 - 1.609 nγ = 1.618 - 1.621 |
Birefringence | δ = 0.021 |
2V angle | Measured from 74° to 78° |
References | [1][2][3] |
Scawtite was first described in 1929 for an occurrence at Scawt Hill in Northern Ireland.[2]
Scawtite occurs as in skarns and hydrothermal veins in limestone. Associated minerals include melilite, spurrite, tobermorite, thomsonite, larnite, grossular, bultfonteinite, calcite, analcime, foshagite and hillebrandite.[1]
References
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