Definition of mafic in US English:



  • Relating to, denoting, or containing a group of dark-colored, mainly ferromagnesian minerals such as pyroxene and olivine.

    Often contrasted with felsic
    • ‘The alternating bands of mafic and felsic minerals are a striking and distinctive feature of all gneisses.’
    • ‘Variably serpentinized Devonian mafic and ultramafic intrusive rocks occur in the western and northern parts of the map area.’
    • ‘If such adiabatic freezing were to control the ascent of hydrous mafic magmas, basalts would probably never erupt in volcanic arcs.’
    • ‘In particular, in most of the eastern part of the complex, mafic minerals are very uncommon.’
    • ‘The Musgrave Block consists of granulite-facies felsic gneisses, granites, felsic and mafic granulites, and voluminous mafic-ultramafic intrusive rocks.’


Early 20th century: blend of magnesium and a contracted form of ferric.