Diorite is a medium-colored (or intermediate), phaneritic igneous rock. This sample is composed of light-colored orthoclase feldspar and quartz crystals and dark-colored hornblende.
Diorite (Photograph by Parvinder Sethi)
Peridotite is a phaneritic, mafic igneous rock. This sample is composed entirely of olivine.
Peridotite (Photograph by Parvinder Sethi)