Dignayan Biyernes- Pyroxenite

In this week’s #DignayanBiyernes, let’s get to know one rock type that is commonly used in construction of buildings and even your households.

Pyroxenite is an ultramafic plutonic igneous rock. It is formed from magma that is rich in iron and magnesium. Its minerals are mostly pyroxenes, making up more than 60% of the rock. You can recognize pyroxenes from their stubby prismatic crystals that are generally dark green to black. 

These minerals give pyroxenite its dark, greenish color. Pyroxenite is relatively rare because it occurs predominantly deep in the crust or the mantle. In the Philippines, they are found together in the same igneous complex with peridotite outcrops.

The featured samples were collected at Sta. Cruz, Zambales in western portion of Luzon Island. They are part of the Zambales Ophiolite, a fragment of Mesozoic oceanic crust that has been emplaced and exposed on land sometime during the Eocene Epoch (56 to 33.9 million years ago). 

Pyroxenites are mined because they may host economically important metals like chromium, nickel, and platinum. If you want to learn more about rocks, you may check out our collections online through this website.

#NationalMuseumPH

Text and photos by NMP Geology and Paleontology Division