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A white, fine-grained potassium mica, usually muscovite in composition, having a silky luster and found as small flakes in various metamorphic rocks.



a variety of white mica, usually muscovite, KAl2[AlSi3O10](OH)2, less commonly, paragonite, NaAl2[AlSi3O10](OH)2. Sericite often contains less potassium (sodium) and more water, SiO2, and MgO and approaches the composition of hydromicas, such as illite and phengite. It is usually encountered as small flakes and scales with a silky luster. As a secondary mineral, sericite is very common in hydrothermally altered igneous and metamorphic rocks, in sericite schists, and in the selvages of ore bodies, where it occurs with quartz, carbonates, chlorite, sulfides, barite, talc, and, less commonly, with fluorite and tourmaline.

References in periodicals archive ?
Within the deeper diorite unit, some intense sericite alteration was observed with arsenopyrite, pyrite and pyrrhotite, generally as selvedges to quartz veins.
In HDPE filled with sericite, mica, kaolin, or diatomite; however, a distinct CI gradient was noted on the sections.
Greisen-type alteration of host rocks occurred early in the Sweet Home hydrothermal system, as part of the higher temperature sericite (muscovite)-fluorite-pyrite-quartz (with topaz inclusions - Wenrich, this issue; Reynolds, this issue)-hubnerite stage of vein mineralization.
Mineralization in drill hole QH-14-01 consists of fine to medium grained disseminated sulphides in sericite altered, sheared quartz monzonite.
A total of 90 samples from the silica sericite alteration zones have been submitted for assay.
We have also completed our surface mapping and sampling program at Andrea which has confirmed the presence of porphyry style mineralization with strongly anomalous copper and gold values associated with broad WNW oriented zones of quartz sericite alteration hosted by a diorite, and we intend to drill test it later this year.
Alteration consists of several highly silicified igneous breccia bodies surrounded by sericite and clay-altered intrusive rocks.
Continuous, uniform gold values were encountered in both drill holes, in a highly altered and mineralized sericite schist--over a true width of 70 m dipping 45-50 degrees south.