Gneissic

Part of speech: adjective

Definitions

1. A form of metamorphic rock characterized by its layered textures and varying mineral groups, often displaying foliation patterns
2. Relating to a specific texture typical of gneiss, featuring distinct bands of diverse minerals and structural orientation
3. Describing a type of metamorphic rock with characteristic banding and varied mineral composition that reflects intense heat and pressure

Etymology: Gneissic describes rock with the banded, layered texture of gneiss. The root word, "gneiss," came into English from German, where "Gneis" was the term miners and geologists used for this coarse, streaked metamorphic rock. The German word is generally traced to a dialect term for rock that splits or sparkles, though that older sense is uncertain. The adjective is simply the noun plus the suffix "-ic," the same ending found in words like "granitic" and "basaltic." Attaching "-ic" to a rock name turns it into a description of the rock's character. So a gneissic outcrop is one that shows the characteristic bands of gneiss, dark and light minerals alternating in stripes.