Felsics

Part of speech: noun

Definitions

  1. A group of light-colored, silica-rich igneous rocks or minerals containing feldspar and quartz commonly found in continental crust ; rocks or minerals characterized by high silica content and alkali feldspar composition often associated with granites ; igneous rock types classified by their light hues and richness in felsic minerals like quartz and feldspars originating from magma rich in silica
  2. Silica-rich volcanic or plutonic rocks composed predominantly of minerals such as feldspar and quartz ; felsic describes igneous compositions with higher alkali and sodium content, typically lighter in color compared to mafic counterparts ; rocks or mineral assemblages marked by abundant felsic components that influence texture and chemical properties in igneous petrology
  3. Rocks or mineral groups that are rich in light-colored minerals like quartz and feldspar, indicative of high silica content ; felsic materials commonly occur in continental crusts and are essential in identifying granite and rhyolite rocks ; igneous petrological category distinguished by mineralogy dominated by feldspars and silica-bearing constituents, influencing rock classification and properties

Etymology: "Felsics" is simply the plural of "felsic," so it refers to more than one such rock or rock assemblage. The adjective "felsic" was built by blending two words: "feldspar" and "silica." Feldspar is the most abundant mineral group in the Earth's crust, and silica (silicon dioxide, the chemical base of quartz) is the second half of the blend. The "-ic" ending is the common English adjective suffix, the same one found in words like "basic" or "metallic." The blend makes sense as a shorthand. Geologists needed a single term for igneous rocks rich in these two constituents, which are the minerals that dominate lighter-colored granites and rhyolites. Its opposite, "mafic," takes its own name from magnesium and ferric iron, the elements that characterize darker rocks such as basalt. The two terms form a pair, with one describing the silica-and-feldspar end of the spectrum and the other the iron-and-magnesium end.

Synonyms: felsic rocks, silicic rocks

Antonyms: mafic rocks, basalts, gabbros