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Bazzite

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Bazzite
Bazzite from Fibbia mountain, Fontana, Central St Gotthard Massif, Leventina, Ticino, Switzerland
General
CategoryCyclosilicate
Formula
(repeating unit)
Be3Sc2Si6O18
Strunz classification9.CJ.05
Crystal systemHexagonal
Crystal classDihexagonal dipyramidal (6/mmm)
H-M symbol: (6/m 2/m 2/m)
Space groupP6/mcc
Unit cella = 9.521 Å, c = 9.165 Å; Z = 2
Identification
ColorLight to dark sky-blue, blue green
Crystal habitAggregates of subparallel prisms
CleavageIndistinct on {0001}
FractureIrregular
TenacityBrittle
Mohs scale hardness6.5 - 7
LusterVitreous
StreakPale bluish white
DiaphaneitySemitransparent
Specific gravity2.77 - 2.85
Optical propertiesUniaxial (-)
Refractive indexnω = 1.622-1.637 nε = 1.602-1.622
Birefringence0.0210
PleochroismO = 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.

It is 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