Schist

Schist

The schists constitute a group of medium-grade metamorphic rocks, chiefly notable for the preponderance of lamellar minerals such as micas, chlorite, talc, hornblende, graphite, and others. Quartz often occurs in drawn-out grains to such an extent that a particular form called quartz schist is produced. By definition, schist contains more than 50% platy and elongated minerals, often finely interleaved with quartz and feldspar. Schist is often garnetiferous.

The individual mineral grains in schist, drawn out into flaky scales by heat and pressure, can be seen by the naked eye. Schist is characteristically foliated, meaning the individual mineral grains split off easily into flakes or slabs. The word schist is derived from the Greek word σχίζειν schíxein meaning "to split", which is a reference to the ease with which schists can be split along the plane in which the platy minerals lie.

Most schists have 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. Certain schists have been derived from fine-grained igneous rocks such as basalts and tuffs. Most schists are mica schists, but graphite and chlorite schists are also common.

Schists are named for their prominent or perhaps unusual mineral constituents, such as garnet schist, tourmaline schist, glaucophane schist, etc.

Schists are frequently used as dimension stone. Dimension stone is stone that has been selected and fabricated to specific shapes or sizes.

Read more about Schist:  Historical Mining Terminology, Formation, Engineering Considerations

Other articles related to "schist, schists":

Haast Schist
... The Haast Schist is a New Zealand schist that is found on the eastern side of the Alpine Fault ... Metamorphic grade progresses from greenschist through biotite schist to garnet schist ... The schists were named after Julius von Haast for his contributions to geology ...
Lizard Complex - Lithologies - Oceanic Complex
... intruded by a suite of dolerite dykes, and a number of schists, split into two broad groups hornblende schist and mica schist ... The hornblende schist, found in contact with the serpentine mass directly to the North (at Ogo Dour) and to the South (at Pentreath and Church Cove) is the metamorphic remnant of basaltic intrusives into ... Structural studies of the hornblende schist indicate that it has been subject to at least three stages of deformation ...
Catalina Schist
... The Catalina Schist is a metamorphic rock complex primarily exposed on Santa Catalina Island, California, that formed during the Cretaceous ... The Catalina Schist is broadly correlated with the Franciscan Complex, a similar metamorphic complex formed along the California margin ... The Catalina Schist is differentiated from the Franciscan primarily in the style of mélange formed during subduction ...
Wissahickon - Geology
... and very distinctive rock of the Wissahickon Creek valley is Wissahickon schist, the predominant bedrock underlying the Philadelphia region, found over a broad swath of southeastern ... In addition to Wissahickon schist, there are layers of quartzite in the valley ... Both schist and quartzite are metamorphic rocks formed from sedimentary deposits of mud and sand that one time were washed from ancient continents into a shallow sea ...