Diabase
Diabase , noun
[French diabase, from Greek dia`basis a crossing or passing over, from dia` + bai`nw to go; -- so called by Brongniart, because it passes over to diorite.]
(Mineralogy) A basic, dark-colored, holocrystalline, igneous rock, consisting essentially of a triclinic feldspar and pyroxene with magnetic iron; -- often limited to rocks pretertiary in age. It includes part of what was early called greenstone.