What is schistosity in rocks?
schistosity, mode of foliation that occurs in certain metamorphic rocks as a consequence of the parallel alignment of platy and lath-shaped mineral constituents. It reflects a considerable intensity of metamorphism—i.e., changes resulting from high temperatures, pressures, and deformation.
What are schists made of?
Most schists are composed largely of platy minerals such as muscovite, chlorite, talc, sericite, biotite, and graphite; feldspar and quartz are much less abundant in schist than in gneiss.
Which metamorphic rock is commonly known for garnet and staurolite Porphyroblasts and schistosity?
schistose
Schist is one of the most widespread rock types in the continental crust. Varieties of schistose metamorphic rocks: 1. Mica schist with porphyroblasts of garnet, staurolite and kyanite. 2.
How does schistosity differ from cleavage?
Schistosity is when minerals that begin to grow in the rock form parallel lines. Disjunctive cleavage is when the cracks are somewhat parallel, with crossovers and zigzags and spaces of undeformed rock in between.
How is schistosity created?
Schistosity is developed at elevated temperature when the rock is more strongly compressed in one direction than in other directions (nonhydrostatic stress). Early stages of metamorphism convert mudstone to a very fine-grained metamorphic rock called slate, which with further metamorphism becomes fine-grained phyllite.
Why is mica shiny?
Mica minerals! They sparkle because light is reflected on their flat surfaces, which are where the mineral breaks along its plane of cleavage. These minerals break so easily along their cleavage that some crystals have broken into many thin layers that look like the pages of a little book.
How do slaty cleavage schistosity and gneissic textures differ from each other?
How do slaty cleavage, schistosity, and gneissic textures differ from each other? These textures differ in that rocks with slaty cleavage break across their layers; rocks with schistosity exhibit layered structures of thin, platy minerals; and rocks with gneissic texture have a solid, banded appearance.
Is slate a schistosity?
The slate easily splits into thin sheets with smooth, flat surfaces. The layering in a coarse grained, crystalline rock due to the parallel arrangement of platy mineral grains such as muscovite and biotite. Foliation in coarse grained metamorphic rocks is called SCHISTOSITY.
Does glass exhibit Conchoidal fracture?
Conchoidal fracture is a smoothly curving fracture surface of fine-grained materials which have no planar surfaces of internal weakness or planes of separation (no cleavage). Such a curving fracture surface is characteristic of glass and other brittle materials with no crystal structure.
What is serpentinite made of?
Serpentine rock is primarily composed of one or more of the three magnesium silicate minerals, “lizardite,” “chrysotile,” and “antigorite.” Chrysotile often occurs as fibrous veinlets in serpentine. Chrysotile in fibrous form is the most common type of asbestos.
Schistosity, mode of foliation that occurs in certain metamorphic rocks as a consequence of the parallel alignment of platy and lath-shaped mineral constituents.
Is schist worth mining?
Schist may be worth mining if it contains useful minerals in large concentration. Common minerals extracted from schistose metamorphic rocks are garnet, kyanite, talc and graphite. A graphite schist sample from Trælen, Norway. This rock is mined because of its very high graphite content.
What is the dominant visible mineral in schist?
Muscovite schist: The dominant visible mineral in this schist is muscovite. Its platy grains are aligned in a common orientation, and that allows the rock to be split easily in the direction of the grain orientation.
What minerals are found in schistose metamorphic rocks?
Common minerals extracted from schistose metamorphic rocks are garnet, kyanite, talc and graphite. A graphite schist sample from Trælen, Norway. This rock is mined because of its very high graphite content. Width of specimen 27 cm.