mica Group of common rock-forming minerals characterized by a platy or flaky appearance. All contain aluminium, potassium and water; other metals, such as iron and magnesium, may be present. Micas have perfect basal cleavage. Common micas are muscovite and the biotite group. Muscovite is commonly found in coarse-grained acidic rocks, schists and gneisses, and in sedimentary rocks. The biotite micas are found in a wide range of igneous and metamorphic rocks, but more rarely in sedimentary rocks.

mi·ca / ˈmīkə/ • n. a shiny silicate mineral with a layered structure, found as minute scales in granite and other rocks, or as crystals. It is used as a thermal or electrical insulator.DERIVATIVES: mi·ca·ceous / mīˈkāshəs/ adj.

MICA

MICA (Heb. מִיכָא; "who is like [El]"), son of *Mephi-Bosheth, son of Jonathan, son of Saul (ii Sam. 9:12). In the genealogical list of the tribe of Benjamin (i Chron. 8:34, 35; 9:40, 41) he is called Micah (Heb. מִיכָה). Thanks to *Jonathan, his grandfather, and Mephi-Bosheth, his father, Mica no doubt benefited from David's generosity (ii Sam. 9:12; cf. 19:24–29).

For his descendants, see *Benjamin.

mica † small plate of talc, etc.; mineral consisting essentially of silicate of aluminium occurring in glittering scales or in crystals. XVIII. — L. mīca grain, crumb; the use in min. was prob. orig. contextual (‘a particle’ of … ); perh. assoc. with L. micāre shine.
Hence micaceous XVIII.