The analcime-phyric rocks of the Crowsnest volcanics are dominated by breccias and epiclastic rocks. Igneous phenocrysts consist of sanidine feldspar, analcime, melanite-garnet, pyroxene, and titanite in a matrix with trachytic alignment of albite and sanidine laths. The Crowsnest Volcanics are altered to zeolite facies and contain veins of analcime±quartz, amygdular prehnite, and pore-filling cement of laumontite. The matrix is recrystallized to quartz, adularia, albite, and chlorite. Calcite veining and pseudomorphs over igneous minerals are also common. The veinal nature of the analcime is interpreted as a product of metamorphic alteration, as opposed to an igneous product. Physical conditions for this metamorphism are constrained by the stability of the zeolite minerals, at 1 to 3 kbar and 180 to 300°C. The potential for economic mineralization is low. Except for mafic inclusions, oxide and sulphide minerals are rare in the Crowsnest Volcanics. XRF whole rock chemistry shows that base metals content is very low.