Many of the granites contain large alkali feldspar phenocrysts. Alkaline magmas enriched with rare-earth elements include carbonatites, peralkaline granites (pegmatites), and nepheline syenite. The mountains consist of sedimentary layers lying upon a basement of granites and gneisses. The continental crust is composed primarily of Archaean, Proterozoic and some Palaeozoic granites and gneisses. Cordierite also occurs in some granites, pegmatites, and norites in gabbroic magmas. They are formed of granites and gneiss. The emerald is highly polished and is found in metamorphic rocks, granites, and mica schist. Some skarns associated with granites also tend to host pegmatites. A-type granites and alkaline igneous provinces usually occur alongside phonolites. This area is hilly to mountainous and consists of Granites and other metamorphic rocks. Granite industry famous for its black, pink and grey granites. Granites and detrital zircons have notably similar and episodic appearances in the rock record. The granites, collectively named the Wichita Granite Group, vary slightly in composition and texture. The modern embankment, inaugurated in 1994, displays an assortment of Karelian granites and marbles. Geologically the area in comprised with Archean Granites and Gneisses.