Microstylolites in a rhyolite porphyry

Abstract The highly unusual occurrence of a diminutive stylolitic structure in a rhyolitic rock is described, and the evidence for the structure's secondary nature is discussed. Solution along these structures. with removal of both quartz and feldspar, is strongly indicated by the partial removal of spherulites and phenocrysts and by the concentration along these microstylolitic seams of the iron oxides which are otherwise more disseminated in the matrix of the rhyolite porphyry. Universal stage observations along these structures indicate their three dimensional irregularity and interpenetrating nature.