an effusive or vein magmatic rock with phenocrysts of alkali feldspar (predominantly albite) and colored minerals (usually biotite and sometimes diopside). The ground mass is compact and consists mainly of isometric or elongated microlites of albite. There are quartz keratophyres, orthoclase keratophyres, and so on (depending upon the light mineral present in them along with the albite). Keratophyres are usually genetically associated with spilites.