leucophyre

Century Dictionary and Cyclopedia

1. n. In petrography, a name given by Gümbel (1874) to certain light-colored altered diabases, with saussuritized feldspars, pale-green augite, and much chlorite. The name having fallen into disuse it has been proposed in the quantitative system of classification of igneous rocks (1902) to apply it, in the classification for field use, to any light-colored porphyry, in distinction to a dark-colored porphyry (melaphyre).