Granodiorite

Part of speech: noun

Definitions

1. A light-colored, coarse-grained igneous rock that primarily includes quartz and feldspar along with other minerals such as biotite, forming through the cooling of magma underground
2. This type of intrusive rock has a composition that predominantly features quartz and feldspar, characterized by a coarse texture and a blend of various minerals, typically formed from cooled magma
3. A coarse-grained igneous rock, often light in color, that mainly contains quartz and feldspar while also featuring minerals like biotite, typically originating from the slow cooling of magma underground

Etymology: Granodiorite is a compound built from two parts. The first, "grano-", comes from Latin "granum", meaning "grain" or "seed", and in geology it signals a coarse, grainy texture visible to the naked eye. The second part is "diorite", the name of a neighbouring rock type, so the word can be read as "a grainy diorite". The sense of grain as the defining feature is the key to the whole term, since the rock's crystals are large enough to see clearly. Granodiorite is an intrusive igneous rock, meaning it formed when magma cooled slowly underground rather than at the surface. Its mineral mix is dominated by quartz and feldspar, with a notable amount of plagioclase feldspar, and it sits between granite and diorite in composition. The naming follows the usual pattern of geology, where a new rock type is described by combining a texture or mineral word with the name of a related rock.