felsinen

Felsinen is a term used in geology to describe rocks with felsic mineralogy—rocks that are rich in light-colored silicate minerals such as feldspars and quartz and relatively low in dark mafic minerals. The term is used in some European geological literature and corresponds to what English-language geology calls felsic rocks.

Chemical and mineralogical characteristics: Felsinen typically have high silica content, on the order of 63 percent or more, and a modal mineralogy dominated by quartz and feldspars, with minor amounts of micas and trace minerals. They are usually light-colored and have lower density than mafic rocks. Texture varies: plutonic examples such as granite and granodiorite are phaneritic, while volcanic counterparts like rhyolite and dacite are aphanitic or porphyritic.

Formation and occurrence: Felsinen forms from partial melting of continental crust and differentiation of magmas, often at tectonically active regions such as convergent margins or hotspots. They crystallize at relatively low temperatures compared with mafic rocks, leading to high-viscosity magmas and often explosive volcanic activity or coarse-grained intrusive bodies.

Classification and examples: The category includes granite, granodiorite, rhyolite, and dacite, among others. While commonly associated with granitic compositions, felsinen is a broader term that covers both plutonic and volcanic rocks that are dominated by felsic minerals.

Importance and usage: Felsinen rocks make up a substantial portion of continental crust and are significant for construction materials, as well as for understanding crustal differentiation and soil formation from weathering of felsic rocks.

Etymology and usage: The term is more common in some languages; in English, felsic is the standard term. See also felsic, granitoid, granitic rock.