Orthopyroxene may occur in high grade metamorphic rocks. It is essential in the granitic gneisses called charnockites, and may be found in pyroxene granulites and metamorphosed iron formations.

Where is pyroxenite found?

Distribution. They frequently occur in the form of dikes or segregations in gabbro and peridotite: in Shetland, Cortland on the Hudson River, North Carolina (websterite), Baltimore, New Zealand, and in Saxony. They are also found in the Bushveld Igneous Complex in South Africa and The Great Dyke in Zimbabwe.

How is orthopyroxene formed?

Metamorphic rocks

At higher grades of regional metamorphism, the amphibole anthophyllite breaks down to form magnesium-iron orthopyroxenes. The orthopyroxene enstatite occurs in high-temperature and high-pressure granulite facies rocks such as quartz-rich, garnet-bearing granulites.