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Formula: Ba(Al2Si6)O16.5H2O
Tectosilicate (framework silicates), brewsterite subgroup, of
the zeolite group,
barium-bearing mineral
Crystal System: Monoclinic
Specific gravity: 2.32 to 2.45
Hardness: 5
Colour: White, Colourless, Pale Pink
Environments
Metamorphic environments
Basaltic cavities
Brewsterite is a hydrothermal mineral deposited in druses lining cavities in
basalt and schist; more
rarely
in hydrothermal veins in ore deposits
(HOM, Dana).
Associated minerals include zeolites,
calcite
and quartz
(HOM).
Localities
At the Marron Volcanics of the Olalla Area South-Central British Columbia, Canada, brewsterite casts after
calcite (pseudomorphs) have
been found at Yellow Lake
(KL p268).
At the Blue Mountain Quarry, Methuen Township, Peterborough County, Ontario, Canada, Brewsterite-Ba occurs in
cavities in prehnite as crystals and aggregates to 1 mm associated with
quartz, diopside,
calcite, wollastonite and
microcline, as well as prehnite
(Min Rec 37-4.288).
Brewsterite-Ba has two co-type localities, Cerchiara Mine, Borghetto di Vara, La Spezia Province, Liguria,
Italy and
Gouverneur Talc Company Number 4 Quarry, Diana Township, Lewis county, New York, USA.
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