ultrabasic
/ˌʌltrəˈbeɪsɪk/
adjective
- Describing igneous rocks that contain very little silica (less than 45%) and are rich in iron and magnesium.
- Geologists study ultrabasic formations to learn about volcanic activity.
- Ultrabasic rocks like peridotite are found deep in the Earth's mantle.
- The ultrabasic composition of the lava made it flow differently than typical basalt.