Definitions

1. adjective

relating to or characteristic of a type of metamorphic rock in which the mineral structure is so finely intergrown that the rock splits into thin flakes or scales

“The geologist carefully examined the phyllitic texture of the ancient rock formation.”

2. noun

a type of metamorphic rock that is characterized by a finely intergrown mineral structure, causing it to split into thin flakes or scales

“The hikers encountered a large boulder of phyllitic rock on the mountain trail.”