The caldera mostly composed from trachytic and phonolitic lavas. Dykes have outcrops of trachytic andesite, dacite and rhyodacite. The case hardening on trachytic clasts of volcanic breccia shows peculiar fabrics. In the volcanic sequence of the hills there is hard basalt lying over trachytic lavas. Massive Trachytic lava flows have been extruded in the past. Phonolites are vesicular and pumiceous in nature, although phonolites with trachytic texture are also present. The caldera-forming eruption was triggered by a basaltic injection into a shallow trachytic magma chamber. Most of the volcano is formed by trachytic lava flows, but hyaloclastite is also found. The Kerichawa Valley Tuff series is a group of pumice-rich trachytic tuffs and agglomerates. The surface texture of the rocks is trachytic to porphyritic. They are of trachytic appearance, containing phenocysts of sanidine, leucite, augite and biotite. Most of the dykes are basaltic in composition but a minority are trachytic. Triangle Dome is a trachytic lava dome in northern British Columbia, Canada. It is a trachytic shield volcano topped by more recent parasitic cones and lava flows. The lower part of the formation is trachytic with abundant sanidine phenocrysts, melanite and pyroxene.