basaltic cavities

The chabazite series comprises five mineral species:
Chabazite-Ca: Ca2[Al4Si8O24]. 13H2O
Chabazite-K: (K2NaCa0.5)[Al4Si8 O24].11H2O
Chabazite-Mg: (Mg0.7K0.5 Na0.1)[Al3Si9O24].10H2O
Chabazite-Na: (Na3K)[Al4Si8O24].11H2 O
Chabazite-Sr: (Sr,Ca)2[Al4Si8O24]. 11H2O
These are all tectosilicates (framework silicates), zeolite group
Specific gravity: 2.08
Hardness: 4½
Streak: White
Colour: Colourless, white, yellow, orange, brown
Solubility: Moderately soluble in hydrochloric acid

Basaltic cavities

Chabazite is found in cavities in basalt associated with stilbite, mesolite, mordenite, heulandite and apophyllite; it is also found in pegmatites.
It is a low temperature mineral. Geothermal wells have been drilled through a thick series of basalt flows in western Iceland, where it was found that chabazite crystallised at temperatures from 55oC to 75oC at depths between 50m and 400m (ZW).

At Willy Wally Gully, New South Wales, Australia, it typically occurs alone in vesicles in basalt, but occasionally it is associated with apatite, lévyne-Ca/offretite, phillipsite, aragonite and/or calcite. It is only rarely associated with more than one other zeolite in the same vesicle. (AJM 16.2.81).

At Abbotsford and Bundoora, inner Melbourne, Victoria, Australia, chabazite-Na occurs in cavities in basalt associated with gonnardite - natrolite, with ferroan calcite, and with phillipsite (AJM 20.1.38-41).

At Rollinsons Quarry, Victoria, Australia, late forming chabazite-Ca was found in some cavities in basalt associated with augite and anorthoclase (AJM 16.2.99).

In Moravia, Czech Republic, chabazite occurs in cavities with axinite, epidote, natrolite, heulandite and stilbite (DHZ 4 p399).

At Palabora, South Africa, chabazite-Ca is found associated with analcime, fluorapophyllite and heulandite (R&M 92.5.436).

In Honolulu, Hawaii, USA, chabazite occurs in basaltic cavities with phillipsite, magnetite and calcite (DHZ 4 p399).

At a road cut prehnite occurrence on the Russell-Hermon Road, St Lawrence County, New York, chabazite-Ca occurs rarely, associated with quartz and calcite (R&M 87.6.541).

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