Metamorphic rocks are derived from igneous or sedimentary rock and sometimes from another metamorphic rock. Metamorphic rocks have very economic uses from building houses to decorations. some gemstones are the metamorphic rock. let’s discuss the most common metamorphic rocks.
Examples of common metamorphic rocks
The slate is formed by low-grade metamorphism of shale. the metamorphism type is regional metamorphism and usually occurs at low temperature and pressure. shale is a sedimentary rock. the slate has foliation called slaty cleavage.
the slate contains feldspar, quartz, and mica. slate may look like shale. slate may be blue, black, purple, grey, red, or green. slates are used for roofing and flooring, electrical panel, and blackboard.
the continuous metamorphism of slate produces phyllite. phyllite has a new mineral assemblage than slate and especially larger grains of mica that can be easily seen with the eye. phyllite is strongly foliated and rich in mica and green chlorite.
Further metamorphism of phyllite produces medium to a coarse-grained rock called schist. schist has schistosity types of foliation. schist contains quartz, biotite, and red garnet.
high-grade metamorphism of shale produces gneiss rock. Gneiss is a very coarse-grained banded rock with irregular foliation. light-colored band of quartz and feldspar are segregated from dark-colored bands of hornblende and biotite. the differences between slate, phyllite, schist, and gneiss are in their grain size.
marble derived from regional and contact metamorphism of calcite limestone and dolomite limestone. marble has an even-grained texture and coarsely crystalline. The pure white marble contains pure calcite grains. the green and white streaky marble contain pyroxene, olivine, and epidote.
the quartzite derived from the recrystallization of sandstone (sedimentary rock). the recrystallization occurs when sandstone undergoes regional or contact metamorphism. Unlike sandstone, quartzite is free from pores. quartzite has an even-grained texture. quartzite is found in white or pinkish color. quartzite is hard and compact.
Amphibolite is formed by the high-grade regional metamorphism of basalt, gabbro, or basic lava. amphibolite is a coarse-grained rock that mainly contains hornblende gneiss.
hornfels is formed by contact metamorphism. It is a fine-grained, hard, splintery rock. the low-grade hornfels contains hornblende, biotite, and pyroxene.
serpentinite is a metamorphic rock formed by regional metamorphism of basic igneous rock. serpentinite is soft, dark-green, irregular streaked rock, serpentinite contains serpentine, talc, chlorite, and calcite.
Uses of metamorphic rock
- Beautiful white colored marble is used in architecture and sculptures.
- Pure quartzite is a source of silica for metallurgical purpose because pure quartzite contains 99 percent quartz.
- slate is used for roofing, flooring, laboratory tabletops, electrical panel, and blackboard.
- Gneiss is used for building sand structure purposes.
- quartzite, marble, schist, and slate are also a building stone. schist is used in jewelry.
- phyllite, serpentinite, and schist are used for decorative purposes such as garden and wall decoration.