Definition of sericite in US English:



  • A fine-grained fibrous variety of muscovite formed by the alteration of feldspar, found chiefly in schist and in hydrothermally altered rock.

    • ‘At some locations sericite completely pseudomorphs topaz and the feldspars.’
    • ‘Many of the grains are partially to entirely replaced by fine-grained sericite and quartz.’
    • ‘The samples from the andesitic units, occurring as tectonic lenses in the greywacke sequence, exhibit plagioclase phenocrysts altered to sericite, calcite and epidote, set in a matrix of chloritized pyroxene and amphibole.’
    • ‘The matrix is dominated by sericite, chlorite and quartz.’
    • ‘The nearby K - 2 deposit is very similar to the Kettle and contains, besides quartz, veins with calcite, ferroan dolomite, and minor chlorite, potassium feldspar, adularia, sericite, pyrite, and barite.’


Mid 19th century: from Latin sericum ‘silk’ + -ite.