Diorite

Diorite is found in Oregon and Washington and is the halfway point in mineral mixtures between gabbro and granite. It is lighter than gabbro and darker than granite or quartz monzonite. Different minerals have different melting and “freezing” temperatures. Diorite is composed of minerals that melt in the medium temperature range and “freeze” at the same rate. As the hot magma containing diorite rises toward the surface, it cools slowly, giving the minerals in the magma time to find one another and form crystals that are quite large.