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on) and hence admitting of ready division into slabs or slates. The common kinds are mica schist, and hornblendic schist, consisting chiefly of quartz with mica or hornblende and often feldspar.

Of a slate color.

Schistose.

Of or pertaining to schist; having the structure of a schist.

The quality or state of being schistose.

A variety of shale or clay slate, containing iron pyrites, the decomposition of which leads to the formation of alum, which often effloresces on the rock.

Characterized by division into four parts.

ancients to kill insects, etc., on vines; -- applied by Brongniart to a carbonaceous alum schist.

one containing much clay. -- Argillaceous iron ore, the clay ironstone. -- Argillaceous schist or state. See Argillite.

Argillaceous schist or slate; clay slate. Its colors is bluish or blackish gray, sometimes greenish gray, brownish red, etc. -- Ar`gil*lit"ic, a.

n structure. They are hydrous silicates of alumina, iron, and magnesia. Chlorite slate, a schistose or slaty rock consisting of alumina, iron, and magnesia.

y; a pug mill. -- Clay pit, a pit where clay is dug. -- Clay slate (Min.), argillaceous schist; argillite. -- Fatty clays, clays having a greasy feel; they are chemical compounds of water, silica, and aluminia, as halloysite, bole, etc. -- Fire clay , a variety of clay, entirely free from lime, iron, or an alkali,…

A name given to the series of sandstones and schists overlying the true nummulitic formation in the Alps, and included in the Eocene Tertiary.

Laminated, but restricted to the variety of laminated structure found in crystalline schist, as mica schist, etc.; schistose.

iffers from gneiss in not having the mica in planes, and therefor in being destitute of a schistose structure.

g considerable iron. Also used as a general term to include the whole species. Hornblende schist (Geol.), a hornblende rock of schistose structure.

ty of potash mica containing water. It is less elastic than ordinary muscovite. Hydromica schist (Min.), a mica schist characterized by the presence of hydromica. It often has a silky luster and almost soapy feel.

The sparingly fossiliferous conglomerates, grits, schists, and states of Great Britain, which lie at the base of the Cambrian system; -- so called, because typically developed in the Longmynd Hills, Shropshire.

a mineral occurs massive. Massive rock (Geol.), a compact crystalline rock not distinctly schistone, as granite; also, with some authors, an eruptive rock.

Partaking of the nature of, or consisting of, mica and lime; -- applied to a mica schist containing carbonate of lime.