Syenite

Common card · No. 325712

Syenite is a coarse-grained intrusive igneous rock with a general composition similar to that of granite, but deficient in quartz, which, if present at all, occurs in relatively small concentrations (< 5%). It is considered a granitoid. Some syenites contain larger proportions of mafic components and smaller amounts of felsic material than most granites; those are classed as being of intermediate composition. The extrusive equivalent of syenite is trachyte.

Read on Wikipedia · Image James St. John, CC BY 2.0