Amphibolite

is a coarse-grained metamorphic rock primarily composed of amphibole minerals (most commonly hornblende) and plagioclase feldspar. It is typically dark-coloured—ranging from dark green to black—and often features a "salt-and-pepper" appearance due to the contrast between dark amphiboles and light-coloured feldspars. This durable rock forms under regional metamorphism at moderate to high temperatures (

) and high pressures, conditions characteristic of the deeper parts of mountain belts. Amphibolite - an overview | ScienceDirect Topics amphibolite