ultramafic
/ˌʌltrəˈmæfɪk/
adjective
- Describing igneous rocks that are very rich in iron and magnesium, and low in silica.
- Ultramafic rocks like peridotite are found deep in the Earth's mantle.
- The ultramafic composition of the mountain made it rich in valuable minerals.
- Geologists study ultramafic formations to understand volcanic activity.
Antonyms