Here's why:

* Peridotite is a mafic igneous rock found deep within the Earth's mantle. It's composed primarily of olivine and pyroxene, with lesser amounts of other minerals like calcium-rich plagioclase feldspar.

* Olivine is a silicate mineral with a green color, rich in magnesium and iron.

* Pyroxene is a group of silicate minerals that come in various colors (green, black, brown).

Peridotite is considered a crucial rock type for understanding the Earth's interior and the processes that drive plate tectonics.