Brewsterite

minerals

zeolite

calcite

pseudomorphs

Formulae:
brewsterite-Ba: Ba(Al2Si6)O16.5H2O
brewsterite-Sr: Sr(Al2Si6)O16.5H2O
Tectosilicates (framework silicates)
Specific gravity: 2.32 to 2.45
Hardness: 5
Streak: Sr White
Colour: Ba: White, Colorless, Pale Pink; Sr: White
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 Yellow lake, near Ollala, British Columbia, Canada, brewsterite casts after calcite (pseudomorphs) have been found (KL p268).

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.

Brewsterite-Sr has its type locality at Strontian, Highland, Scotland, UK.

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