WGNHS
Wisconsin Geological and Natural History Survey

Phillipsite

White phillipsite crystal clusters on matrix. From Rock Island Dam, Douglas County, Washington. Field of view is about 2 mm. Specimen was collected by zeolite expert Rudy Tschernich. (Image courtesy Douglas Merson; unauthorized reproduction is prohibited.)

Formula: (K,Na,Ca,Ba)4-7(Al4-7Si12-9)O32.12H2O Monoclinic

Description:

White phillipsite-K crystals on matrix. From Nickel Quarry, Oberwiddersheim, Hungen, Volgelsburg, Hesse, Germany. Specimen is 4.5 x 4.5 x 2 cm in size. (Photo courtesy Dan and Diana Weinrich Minerals; unauthorized reproduction is prohibited.)

Phillipsite is a member of the zeolite family. It occurs most frequently in vein and amygdule fillings in basaltic rocks. It also forms during shallow burial of volcanic rocks, particularly ashes and glasses.

DOUGLAS COUNTY: Phillipsite has been tentatively identified in thin veins with natrolite (?) and calcite in gouge cutting basalt along the Douglas Fault exposed along the banks of the Amnicon River in Amnicon Falls State Park (SE sec. 29 T.48N. R.12W.) (Ludvigson and Anderson, 1986).