The phillipsite minerals are tectosilicates (framework silicates) of the zeolite group, comprising:
Phillipsite-Ca: Ca3(Si10Al6)O32.12H2O
Phillipsite-K: K6(Si10Al6)O32.12H2O
Phillipsite-Na: Na6(Si10Al6)O32.12H2O
Phillipsite forms a series with harmotome
Specific gravity: 2.2
Hardness: 4 to 5
Streak: White
Colour: White
Solubility: Moderately soluble in hydrochloric acid

Sedimentary environments
Hydrothermal environments
Basaltic cavities (most commonly)

Phillipsite is a common zeolite in basaltic cavities, ore veins, lithified rhyolitic vitric tuff, saline lake deposits and ocean floor sediments. It forms in Iceland in geothermal wells at 60 to 85oC
Phillipsite is a mineral of the zeolite facies


At the Kulnura quarry, Central Coast, New South Wales, Australia, colourless and pale yellow to dark orange crystals of phillipsite to 0.7 mm occur within fractures in sedimentary xenoliths and throughout basanite at the Kulnura volcano. The lighter coloured crystals are phillipsite-(K) and the darker ones are phillipsite-(Na). The colour may be due to minor iron within the phillipsite crystal, or to hematite/ goethite coating micro fractures and occuring in spaces between crystals. Vesicles within the basanite are filled with chabazite, calcite and phillipsite, and secondary mineralisation along joints is commonly analcime, natrolite, calcite and phillipsite (AJM 21.1.7-17)

In the basaltic rocks near Kladno, Czechoslovakia, phillipsite is associated with thomsonite, mesolite, chabazite and natrolite, and it is always the first of these minerals to have been formed (DHZ 4 p398).

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