a complex of volcanogenic albitized rocks—spilites and keratophyres and their tuffs and tuff-breccias—that have formed as the result of underwater volcanic eruptions in the early developmental stages of primary geosynclinal troughs. Extensive development of spherulitic lavas is typical of spilite-keratophyre formations; traces of marine fauna may be found in the tuffs. The characteristic alteration of rocks of spilite-keratophyre formations, which leads to chloritization of glass and albitization, is believed to be linked to metamorphism in the upper parts of a greenstone facies. Spilite-kerato phyre formations are often an important component of ophiolitic strata.