mafic

Blend of magnesium +‎ ferric.

• (UK) IPA^(key): /ˈmafɪk/
• (US) IPA^(key): /ˈmeɪfɪk/, /ˈmæfɪk/

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mafic (comparative more mafic, superlative most mafic)

1. (geology) Describing rocks, such as silicate minerals, magmas, and volcanic and intrusive igneous rocks, which contain relatively high concentrations of magnesium and iron.

   Synonyms: ferromagnesic, basic

   Antonyms: felsic, acidic

   • 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.

   • 2004, Richard Fortey, The Earth, Folio Society, published 2011, page 60:

     As a whole, rocks of this type are referred to as mafic, because of the importance of magnesium and iron in their composition.

mafic (plural mafics)

1. A rock with such properties.