Keratophyre

Keratophyre is a volcanic rock of intermediate composition.

[1] Keratophyre forms lava flows and subvolcanic intrusions (dykes and sills).

Keratophyre occurs, for example, at Hüttenrode in the Harz Mountains of Germany and in the Berwyn Hills of Wales.

[2] Keratophyre tuff of Early Devonian age occurs in Sauerland (Germany).

[3] The term quartz keratophyre has traditionally been used in the Nordic countries to describe a metamorphosed, felsic extrusive rock, corresponding to rhyolite, dacite, or rhyodacite according to IUGS terminology.