Formula: KCa4Si8O20(F,OH).8H2O Tetragonal
Description: Apophyllite series minerals form from low temperature hydrothermal fluids. It is particularly common in veins within gabbros and basalts.
DOUGLAS COUNTY: White to pink cleavage masses and crude platy crystals several centimeters across occur with prehnite in veins cutting gabbros in the Buckley Quarry, near Amnicon Falls (NW Sec. 32 T.48N. R.12W.) (Cordua, 1991).