schist

(redirected from Hornblende schist)
Also found in: Dictionary, Thesaurus, Wikipedia.

schist

(shĭst), metamorphic rockrock,
aggregation of solid matter composed of one or more of the minerals forming the earth's crust. The scientific study of rocks is called petrology. Rocks are commonly divided, according to their origin, into three major classes—igneous, sedimentary, and metamorphic.
..... Click the link for more information.
 having a foliated, or plated, structure called schistosity in which the component flaky minerals are visible to the naked eye. 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. Schists split readily along their planes of schistosity, like slates along cleavage lines. Like other foliated rocks, schists owe their origin to the metamorphism of preexisting rocks. The commonest of the schists is mica schist, the essential minerals of which are quartzquartz,
one of the commonest of all rock-forming minerals and one of the most important constituents of the earth's crust. Chemically, it is silicon dioxide, SiO2.
..... Click the link for more information.
 and micamica
, general term for a large group of minerals, hydrous silicates of aluminum and potassium, often containing magnesium, ferrous iron, ferric iron, sodium, and lithium and more rarely containing barium, chromium, and fluorine.
..... Click the link for more information.
 (biotite or muscovite). Other schists are hornblende schist, talc schist, chlorite schist, and graphite schists. Schists are abundant in the Precambrian (Archean and Proterozoic) rocks.

schist

[shist]
(geology)
A large group of coarse-grained metamorphic rocks which readily split into thin plates or slabs as a result of the alignment of lamellar or prismatic minerals.

schist

A rock, the constituent minerals of which have assumed a position in more or less closely parallel layers or folia; due to metamorphic action; used principally for flagging.

schist

any metamorphic rock that can be split into thin layers because its micaceous minerals have become aligned in thin parallel bands
References in periodicals archive ?
Protoliths of hornblende schists correspond to basic and volcano-sedimentary rocks.
This deformation phase is defined by actinolite, chlorite and muscovite in the greenschists (Figures 3a y 3b), by hornblende in the hornblende schists (Figure 3c) and the amphibolites (Figure 3e), by chlorite, muscovite and graphite in quartz-muscovite-chlorite schists or mica schists (Figures 3h and 30, and by hornblende and anthophyllite in the anthophyllite schists (Figure 3j).
Thereby, in the Arquia Group type section, the greenschists change in a transitional form to hornblende schists westward, and the amphibolites appear further to the west.
This is supportd by the mineralogy of greenschist facies that is found among the mineral assemblages of the amphibolite and epidote-amphibolite facies, such as chlorite + actinolite + epidote minerals + quartz (mineralogy of greenschist facies), between hornblende + epidote minerals + quartz + albite [+ or -] garnet (mineralogy of epidote-amphibolite facies) in the hornblende schists (Figures 4d), and the chlorite + muscovite + epidote minerals + plagioclase (albite) + quartz (mineralogy of greenschist facies) between the hornblende + garnet + plagioclase [+ or -] quartz (amphibolite facies) in the garnet amphibolites (Figure 3f).