Definitions

1. noun

A type of igneous rock consisting of intergrown crystals of orthoclase and plagioclase feldspar, typically exhibiting a mottled or patchy appearance.

“The geologist examined the perthite outcropping and noted its unique crystal structure.”

2. adjective

Relating to or characterized by perthite.

“The perthite-rich rocks found in the region were of great interest to geologists.”