felsic

English

Etymology

Blend of feldspar +‎ silica, +‎ -ic.

Pronunciation

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Adjective

felsic (comparative more felsic, superlative most felsic)

1. (petrology) Enriched in minerals predominantly composed of the lighter elements such as silicon, oxygen, aluminium, sodium, and potassium.

   Synonyms: acidic, sialic, silicic

   Coordinate term: mafic

   • 1954, J. C. Olson, D. R. Shawe, L. C. Pray, W. N. Sharp, Rare-Earth Mineral Deposits of the Mountain Pass District, San Bernadino County, California, U.S. Geological Survey, Professional Paper 261, page 22:

     Much of the southern half of the southeastern body is a mafic syenite, slightly more felsic than the shonkinite.

   • 1983, Paul C. Bateman, “A summary of critical relations in the central part of Sierra Nevada batholith, California, U.S.A.”, in J. A. Roddick, editor, Circum-Pacific Plutonic Terranes‎^[1], Geological Society of America, Memoir 159, page 241:

     Within comagmatic suites, successively younger granitoids are commonly, but not invariably, more felsic, representing progressively lower temperature mineral assemblages.

   • 1992, David C. Champion, Bruce W. Chappell, “Petrogenesis of felsic I-type granites: an example from northern Queensland”, in P. E. Brown, B. W. Chappell, editor, The Second Hutton Symposium on the Origin of Granites and Related Rocks‎^[2], Geological Society of America, Special Paper 272, page 115:

     The Claret Creek Supersuite granites are a little more felsic (65-77% ${\ce {SiO2}}$), and are chemically distinctive, having higher ${\ce {Al2O3}}$, ${\ce {CaO}}$, ${\ce {Na2O}}$ and ${\ce {Sr}}$, and lower ${\ce {K2O}}$, ${\ce {Rb}}$, ${\ce {Th}}$ and ${\ce {U}}$ than the granites of the Almaden Supersuite.

Derived terms

• felsification
• nonfelsic

Related terms

• felsite

Noun

felsic (plural felsics)

1. A rock with such properties.
   • 1953, R. C. Emmons, “Petrogeny of the Syenites and Nepheline Syenites of Central Wisconsin”, in R. C. Emmons, editor, Selected Petrogenic Relationships of Plagioclase‎^[3], Geological Society of America, Memoir 52, page 80:

     The central part of this nepheline syenite is very white felsics with black mafics in it. The entire area contains many nepheline-bearing dike rocks, but almost all are gray or pink or even red due to the color in the felsics.

   • 1992, T. E. Smith, chapter 1, in K. C. Condie, editor, Proterozoic Crustal Evolution, Elsevier, page 35:

     There are also calcalkaline felsics that have highly enriched LREE^{[light rare-earth element]} patterns with lower overall abundances.

Anagrams

• lesfic