Argillaceous schist is metamorphic rock which exhibits fine laminations of clay materials. Categories: Mineral stubs | Metamorphic rocks ... The term Metamorphic can be associated with a number of meanings:- Metamorphic rock The term for rocks that have been transformed by extreme heat and pressure. ...
The schists form a group of metamorphic rocks chiefly notable for the preponderance of lamellar minerals such as micas, chlorite, talc, hornblende, graphite, etc. Quartz often occurs in drawn-out grains to such an extent that quartz schist is produced.
Most schists have in all probability been derived from clays and muds[?] which have passed through a series of metamorphic processes involving the production of shales, slates and phyllites[?] as intermediate steps.
Schists are named for their prominent or perhaps unusual mineral constituents, such as garnet schist, tourmaline schist, glaucophane[?] schist, etc. The word schist is derived from the Greek meaning to split, which is in reference to the ease with which schists can be split along the plane in which the platy minerals lie.
Schists are distinguished from the other foliated rocks, slates and gneisses, by the size of their mineral crystals; these are larger than those of slates, being visible to the naked eye, but smaller than those of gneisses, which are coarsely foliated rocks as opposed to finely foliated, or schistose, rocks.
As contrasted with the folia of slates, the folia of schists are rough-surfaced and irregular.
The commonest of the schists is mica schist, the essential minerals of which are quartz and mica (biotite or muscovite).
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