Meionite

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Meionite
Meionite-Quartz-53866.jpg
Meionite (scapolite) crystals (cross-shaped) in a quartz matrix, 7.2 x 4.0 x 3.0 cm. Worcester County, Massachusetts.
General
Category Tectosilicate < br/>Scapolite group
Formula
(repeating unit)
Ca4Al6Si6O24CO3
Strunz classification 9.FB.15
Crystal system Tetragonal
Crystal class Dipyramidal (4/m)
(same H-M symbol)
Space group I4/m
Unit cell a = 12.179(1) Å, c = 7.571(1) Å, Z = 2
Identification
Color Colorless, white, grey, pink, violet, blue, yellow, orange-brown, brown
Cleavage Distinct/good on {100}{110}
Fracture Irregular/uneven, conchoidal
Tenacity Brittle
Mohs scale hardness 5 - 6
Luster Vitreous, resinous, pearly
Streak White
Diaphaneity Transparent, opaque
Specific gravity 2.74 - 2.78
References [1][2][3][4]

Meionite is a tectosilicate belonging to the scapolite group with the formula Ca4Al6Si6O24CO3. Some samples may also contain a sulfate group. It was first discovered in 1801 on Mt Somma, Vesuvius, Italy.

References[edit]