K-Phillipsite - K₆(Si₁₀Al₆)O₃₂ * 12H₂O

Phillipsite (member of phillipsite group of the zeolite group), was first described by Lévy (1825) from the type locality Aci Reale, now Acireale, on the slopes of Etna, Sicily, Italy. The mineral was named after William Phillips, author of geological and mineralogical treatises and a founder of the Geological Society of London. The phillipsite series was divided into species by the Subcommittee on Zeolites of the International Mineralogical Association, Commission on New Minerals and Mineral Names (Coombs et al. 1997).

The species names are based on the dominant channel cation:

Phillipsite-Na: has the composition from the original type locality at Aci Castello, Sicily, Italy.
Phillipsite-K: original type locality at Capo di Bove, Rome, Italy.
Phillipsite-Ca: original type locality at Lower Salt Lake Tuff, Oahu, Hawaii.

Minerals of the phillipsite series occur in many different environments, including amygdaloidal filling of cavities in basaltic rocks and replacement of rhyolitic vitric tuff and welded tuff in terrestrial settings. They are an abundant authigenic constituent of deep sea sediment world-wide.

Cavities in basaltic lavas
Phillipsite occurs in basalt cavities in many localities around the world. The cation composition of the phillipsite is controlled to some extent by the host lava composition, such as phillipsite-K in the leucitite of Capo di Bove, but more importantly, early precipitated phases may deplete pore fluids in a major cation. For example, early calcite formation will greatly enhance the alkali content of phillipsite and other zeolites.
Common associated minerals are chabazite, analcime, thomsonite, natrolite, and many other zeolites and hydrated calcium silicates. Most occurrences are consistent with diagenetic or low temperature hydrothermal alteration (65-85°C) of the host basalt.

Optical Properties:
• Form: Equant to prismatic, or most common in spherical radiating aggregates.
• Color: Colorless in thin section.
• Relief: Moderate.
• Birefringence: Very low.

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Sample of Limburgite with vesicles filled by philipsite. From Mineral forum.

Sample of Limburgite with vesicles filled by philipsite. From From Geologische Streifzüge

Bibliography

• Bass, M.N. 1976. Secondary minerals in oceanic basalts, with special reference to Leg 34, Deep Sea Drilling Project, in Yeats, R.S. et al., eds., Initial Reports of the Deep Sea Drilling Project, XXXIV, U.S. Gov. Printing Office, Washington, D.C., 393-432.
• Weisenberger, T. and Spürgin, S. 2009. Zeolites in alkaline rocks of the Kaiserstuhl Volcanic Complex, SW Germany – New microprobe investigation and the relationship of zeolite mineralogy to the host rock. Geologica Belgica, 12, 75-91.

Photo
Augite crystals within a glassy groundmass and vesicles with phillipsite crystals. Limberg, Kaiserstuhl, Germany. XPL image, 1x (Field of view = 9mm)	Augite crystals within a glassy groundmass and vesicles with phillipsite crystals. Limberg, Kaiserstuhl, Germany. PPL image, 1x (Field of view = 9mm)	Augite crystals within a glassy groundmass and vesicles with phillipsite crystals. Limberg, Kaiserstuhl, Germany. XPL image, 1x (Field of view = 9mm)
Augite crystals within a glassy groundmass and vesicles with phillipsite crystals. Limberg, Kaiserstuhl, Germany. PPL image, 2x (Field of view = 7mm)	Augite crystals within a glassy groundmass and vesicles with phillipsite crystals. Limberg, Kaiserstuhl, Germany. PPL image, 2x (Field of view = 7mm)	Augite crystals within a glassy groundmass and vesicles with phillipsite crystals. Limberg, Kaiserstuhl, Germany. XPL image, 2x (Field of view = 7mm)
Phillipsite crystals filling a volcanic vesicle. Limberg, Kaiserstuhl, Germany. PPL image, 2x (Field of view = 7mm)	Phillipsitee crystals filling a volcanic vesicle. Limberg, Kaiserstuhl, Germany. XPL image, 2x (Field of view = 7mm)	Phillipsite crystals filling a volcanic vesicle. Limberg, Kaiserstuhl, Germany. XPL image, 2x (Field of view = 7mm)
Phillipsite crystals filling a volcanic vesicle. Limberg, Kaiserstuhl, Germany. PPL image, 2x (Field of view = 7mm)	Phillipsite crystals filling a volcanic vesicle. Limberg, Kaiserstuhl, Germany. XPL image, 2x (Field of view = 7mm)	Phillipsite crystals filling a volcanic vesicle. Limberg, Kaiserstuhl, Germany. PPL image, 2x (Field of view = 7mm)
Phillipsite crystals filling a volcanic vesicle. Limberg, Kaiserstuhl, Germany. XPL image, 2x (Field of view = 7mm)	Phillipsite crystals filling a volcanic vesicle. Limberg, Kaiserstuhl, Germany. PPL image, 2x (Field of view = 7mm)	Phillipsite crystals filling a volcanic vesicle. Limberg, Kaiserstuhl, Germany. XPL image, 2x (Field of view = 7mm)
Phillipsite crystals filling a volcanic vesicle. Limberg, Kaiserstuhl, Germany. XPL image, 10x (Field of view = 2mm)	Phillipsite crystals filling a volcanic vesicle. Limberg, Kaiserstuhl, Germany. XPL image, 10x (Field of view = 2mm)	Phillipsite crystals filling a volcanic vesicle. Limberg, Kaiserstuhl, Germany. XPL image, 10x (Field of view = 2mm)
Phillipsite crystals filling a volcanic vesicle. Limberg, Kaiserstuhl, Germany. XPL image, 10x (Field of view = 2mm)	Phillipsite crystals filling a volcanic vesicle. Limberg, Kaiserstuhl, Germany. PPL image, 10x (Field of view = 2mm)	Phillipsite crystals filling a volcanic vesicle. Limberg, Kaiserstuhl, Germany. XPL image, 10x (Field of view = 2mm)
Phillipsite crystals filling a volcanic vesicle. Limberg, Kaiserstuhl, Germany. XPL image, 10x (Field of view = 2mm)	Phillipsite crystals filling a volcanic vesicle. Limberg, Kaiserstuhl, Germany. PPL image, 20x (Field of view = 2mm)	Phillipsite crystals filling a volcanic vesicle. Limberg, Kaiserstuhl, Germany. XPL image, 20x (Field of view = 2mm)
Phillipsite crystals filling a volcanic vesicle. Limberg, Kaiserstuhl, Germany. XPL image, 20x (Field of view = 2mm)	Phillipsite crystals filling a volcanic vesicle. Limberg, Kaiserstuhl, Germany. XPL image, 20x (Field of view = 2mm)	Phillipsite crystals filling a volcanic vesicle. Limberg, Kaiserstuhl, Germany. XPL image, 20x (Field of view = 2mm)