Bazzite

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Bazzite
Bazzite - Fibbia Ticino Switzerland.jpg
Bazzite from Fibbia mountain, Fontana, Central St Gotthard Massif, Leventina, Ticino, Switzerland
General
Category Cyclosilicate
Formula
(repeating unit)
Be3Sc2Si6O18
Strunz classification 9.CJ.05
Crystal system Hexagonal
Crystal class Dihexagonal dipyramidal (6/mmm)
H-M symbol: (6/m 2/m 2/m)
Space group P6/mcc
Unit cell a = 9.521 Å, c = 9.165 Å; Z = 2
Identification
Color Light to dark sky-blue, blue green
Crystal habit Aggregates of subparallel prisms
Cleavage Indistinct on {0001}
Fracture Irregular
Tenacity Brittle
Mohs scale hardness 6.5 - 7
Luster Vitreous
Streak Pale bluish white
Diaphaneity Semitransparent
Specific gravity 2.77 - 2.85
Optical properties Uniaxial (-)
Refractive index nω = 1.622-1.637 nε = 1.602-1.622
Birefringence 0.0210
Pleochroism O = pale greenish yellow; E = intense sky-blue
References [1][2][3][4]

Bazzite is a beryllium scandium cyclosilicate mineral with chemical formula: Be3Sc2Si6O18[2] (Be3(Sc,Fe)2Si6O18[3] or Be3(Sc,Al)2Si6O18[4]). It crystallizes in the hexagonal crystal system typically as small blue hexagonal crystals up to 2 cm length. It has a Mohs hardness of 6.5-7 and a specific gravity of 2.77 to 2.85.

Hard to distinguish from blue beryl.

Occurs in miarolitic cavities in granite, in alpine veins and in scandium bearing granitic pegmatites. It occurs associated with quartz, orthoclase, muscovite, laumontite, albite, hematite, calcite, chlorite, fluorite, beryl and bavenite.[3]

It was first described from an occurrence in Baveno, Italy. Named after the discoverer, the Italian engineer Alessandro E. Bazzi.[3]

References[edit]