noun
- Plural of nephelinite; volcanic rocks composed primarily of nepheline and pyroxene, with little or no feldspar.
Usage: geology; technical
Examples
- Nephelinites are rare volcanic rocks found in certain alkaline igneous provinces.
- The geologist identified nephelinites in the sample collected from the volcanic field.
- Nephelinites differ from basalts in their mineral composition and formation conditions.
- These nephelinites contain nepheline as a primary mineral phase.