What is diabase in geology ?

Diabase : definition

Diabase is a term often used as a synonym for dolerite (subvolcanic vein rock with ophitic texture similar to basalts). It designates both healthy rock and rock strongly altered by ouralitization (transformation of pyroxenes and a mixture of green hornblende and actinote) and by alteration of plagioclases and other ferromagnesian minerals; the diabase then takes on a characteristic dark green tint.