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Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism. The original rock ( protolith ) is subjected to temperatures greater than 150 to 200 °C (300 to 400 °F) and, often, elevated pressure of 100 megapascals (1,000 bar ) or more, causing profound physical or chemical changes.
The black crystal is garnet, the pink-orange-yellow colored strands are muscovite mica, and the brown crystals are biotite mica. The grey and white crystals are quartz and (limited) feldspar. Metamorphism is the transformation of existing rock (the protolith) to rock with a different mineral composition or texture.
Slate. Slate is a fine-grained, foliated, homogeneous, metamorphic rock derived from an original shale -type sedimentary rock composed of clay or volcanic ash through low-grade, regional metamorphism. It is the finest-grained foliated metamorphic rock. [1] Foliation may not correspond to the original sedimentary layering, but instead is in ...
Claystone – Clastic sedimentary rock composed primarily of clay-sized particles. Coal – Combustible sedimentary rock composed primarily of carbon. Conglomerate – Sedimentary rock composed of smaller rock fragments. Coquina – Sedimentary rock that is composed mostly of fragments of shells.
A skarn is formed by a variety of metasomatic processes during metamorphism between two adjacent lithologic units. Skarns can form in almost any rock type such as shale, granite, or basalt but the majority of skarns are found in carbonate rocks containing limestone or dolomite. It is common to find skarns near plutons, along faults and major ...
Hornfels. Hornfels is the group name for a set of contact metamorphic rocks that have been baked and hardened by the heat of intrusive igneous masses and have been rendered massive, hard, splintery, and in some cases exceedingly tough and durable. [1] These properties are caused by fine grained non-aligned crystals with platy or prismatic ...
Schist (/ ˈʃɪst / SHIST) is a medium-grained metamorphic rock showing pronounced schistosity (named for the rock). This means that the rock is composed of mineral grains easily seen with a low-power hand lens, oriented in such a way that the rock is easily split into thin flakes or plates. This texture reflects a high content of platy ...
Rock formations in Ongamira Valley, Sierras de Córdoba, Argentina. Belogradchik Rocks, Balkan Mountains, Bulgaria. "Jaws", an erosional fin in Little Finland, Nevada, US. "Hajdučka vrata" on Čvrsnica, Herzegovina. Paklenica, Croatia. Devil's Town, Serbia. Three Sisters in Blue Mountains, Australia. A rock formation is an isolated, scenic, or ...