Other minerals are present in small amounts. Marble is more compact than limestone since its porosity is reduced by pressure and recrystallization. In the course of cementation by silica, quartz sandstones or siltstones may become so completely cemented with quartz that porosity is practically eliminated. Textural features: Parallel fabric of platy minerals – Rock cleaves into platy pieces. Textural features: Granular, sometimes banded, no foliation. If foliation is not strong it may be used for crushed stone. Slate is another common metamorphic rock that forms from shale. It can often be seen in road cuts, stream channels and on hill tops and usually stands out from the intervening schists. List of top sixteen metamorphic rocks:- 1. There are many varieties of schists based on the minerals. The perfection of schistosity varies. They are weak due to foliation. The common minerals whose dimensional parallelism determines schistosity are muscovite, biotite, chlorite and hornblende. Textual features: Parallel fabric of glaucophane forms planes of weakness, rock cleaves into thin platy pieces. Textural features: Even textured, Sugary grain size, often finely banded. Limestone, a sedimentary rock, will change into the metamorphic rock marble if the right conditions are met. Before publishing your articles on this site, please read the following pages: 1. Chemical group: Calcium carbonate – silicate, Science, Types, Geology, Rocks, Metamorphic Rocks. This is a massive, hard compact to fine grained metamorphic rock developed in contact with large igneous intrusions (by contact metamorphism). The mineralogy of phyllite is similar to that of slate and the rock is a product of more intense and longer continued metamorphism. While in slates, the foliation is called Slaty cleavage, the foliation of schists is called Schistosity. The alternating bands or layers are commonly of unlike mineral composition. This rock represents one of the highest grades of regional metamorphism. Phyllite is a finely laminated, finely micaceous rock of nearly uniform composition, with a distinct silky lustre on the foliation surfaces. Other minerals: Amphibole, Forsterite, Epidote, Mica, Garnet, Magnetite, Plagioclase, Pyrite, Quartz, Serpentine, Wollastonite, Colour: White, Pale pinkish, Greenish Grey. Schists are of little use. They are formed by both thermal as well as dynamic metamorphism. Although usually this rock is composed of light minerals, the colour of hornfels, because of impurities is often dark, grey to black, greenish and occasionally tending to white. When subjected to additional heat during contact with large igneous intrusions, additional minerals like andalusite can give the slate a spotted appearance. The host rock is a gneiss-like metamorphic rock and the intruding or injected rock is a granitic igneous rock. Copyright 10. The specimen shown above is about two inches (five centimeters) across. Nicely coloured chlorite varieties of chlorite schist are used as decorative stones for flooring slabs and cladding. Although metamorphic rocks typically form deep in the planet’s crust, … Marble develops smooth, sometimes grooved, weathered surfaces and is sparkling or granular in broken surfaces. Typical minerals: Essential blue amphibole (glaucophane), Other minerals: Albite, Calcite, Garnet, Quartz, Mica, Talc. Marbles range in texture from fine to relatively coarse varieties in which the grains are clearly visible to the unaided eye. This rock can form massive bodies retaining recognizable basalt-like intrusive forms like dikes. It occurs in many colours. Mica Schist containing abundant muscovite, biotite or chlorite is the usually recognized type which shows shiny surfaces if broken. Slate is formed from low grade regional metamorphism of fine grained sedimentary mudrocks. This rock consists of two different clearly recognizable rock types which are interdigitated with sharp boundaries. Green Schist 11. It is significant in prospecting for ores, since it may be associated with copper and nickel deposits. Its even strength makes it a popular stone for buildings and ornamental purposes. As metamorphism is repeated at lower pressure in the presence of water, the Olivine in Peridotite is replaced by serpentine and talc, sometimes producing serpentine rock (serpentinite). There are many varieties of this rock based on the dominant minerals. Ex: Andalusite hornfels and pyroxene hornfels. Textual features: Even textured rock. A common pattern grades from unaltered dolomite to a tremolite zone, then to a narrower diopside zone and finally to an inner wollastonite and garnet zone. The banding may be due to differences in the original sedimentary rock, due to segregation and recrystallization of the material of igneous rocks or due to a crude foliation resulting from shearing and recrystallization. Other minerals: Any rock forming minerals – Feldspar, Mica, Chlorite, Garnet. It contains a number of other flaky minerals whose parallel alignment produces sheets-like foliation. These rocks are produced by contact metamorphism of limestone’s. Content Filtrations 6. Hornfels are metamorphic rocks formed through the process of contact metamorphism. The micas too are recrystallized and made to lie with their leaves parallel to the long axes of the crystals. Marble 7. Elongated amphibole crystals, sometimes aligned. There are also varieties of green schist dominated by different green minerals like Actinolite schist. It is composed primarily of hornblende (amphibole) and plagioclase, usually with very little quartz.