1. Peridotite: This is a dense, dark-colored, igneous rock that makes up the majority of the Earth's upper mantle. It's rich in minerals like olivine and pyroxene.

2. Eclogite: This is a high-pressure metamorphic rock that forms deep within the Earth's mantle. It's composed mainly of garnet and pyroxene.

While peridotite is more abundant, both play crucial roles in the Earth's structure and processes.