Definition

Noun A dark, fine-grained volcanic rock composed primarily of the minerals nepheline and pyroxene, with little to no feldspar. It is an igneous rock, meaning it formed from the cooling and solidification of magma or lava.

Usage

The term "nephelinite" is used specifically in geology and petrology to classify a type of volcanic rock. It is a technical term. * The geologist identified the dark outcrop as nephelinite. * Nephelinite is often found in volcanic regions associated with continental rifting. * The composition of this lava flow is primarily nephelinite.

Advanced Usage

• Petrogenesis: In scientific discussions, "nephelinite" is used to describe magmas derived from low degrees of partial melting of the Earth's mantle, often under high pressure. Its presence can indicate specific tectonic settings.
  • The nephelinite magmas in this province suggest a deep mantle source.

Variants and Related Words

• Nepheline (noun): A feldspathoid mineral, a key component of nephelinite.
• Nephelinitic (adjective): Describing rocks or textures related to or characteristic of nephelinite.
  • The sample showed a nephelinitic texture under the microscope.

Synonyms

• Alkali basalt (a broader category that may include nephelinitic compositions)
• Volcanic rock (general term)

Different Meanings

The word "nephelinite" has no other common meanings outside of its specific geological definition.

Noun

1. an igneous rock consisting of nepheline and pyroxene