A Metamorphic Rock Formed From Granite

Gneissgranite gneiss is a metamorphic rock formed from granite gneiss schist quartzite.

A metamorphic rock formed from granite.

It is formed by dynamic metamorphism at high temperatures and high pressures that aligns the grains of mica hornblende and other flat or elongated minerals into thin layers or foliation. The original rock is subjected to heat temperatures greater than 150 to 200 c and pressure 100 megapascals 1 000 bar or more causing profound physical or chemical change the protolith may be a sedimentary igneous or existing metamorphic rock. Gneiss is formed by high temperature and high pressure metamorphic processes acting on formations composed of igneous or sedimentary rocks. Metamorphic rocks arise from the transformation of existing rock types in a process called metamorphism which means change in form.

Gneiss ˈnaɪs is a common and widely distributed type of metamorphic rock. In migmatite you can see metamorphic rock that has reached the limits of metamorphism and begun transitioning into the igneous stage of the rock cycle by melting to form magma. Schist comes from the ancient greek for split through latin and french. Slate is another common metamorphic rock that forms from shale.

Foliated means the parallel arrangement of certain mineral grains that gives the rock a striped appearance foliation forms when pressure squeezes the flat or elongate minerals within a rock so they become aligned. Granite is an igneous rock that forms when magma cools relatively slowly underground. A photograph of polished gneiss from the stock of a countertop vendor. What rock does granite form from heat and pressure.

The preexisting rocks may be igneous sedimentary or other metamorphic rocks. Some kinds of metamorphic rocks granite gneiss and biotite schist are two examples are strongly banded or foliated. These rocks develop a platy or sheet like structure that reflects the direction that pressure was applied. It is usually composed primarily of the minerals quartz feldspar and mica.

Orthogneiss is gneiss derived from igneous rock such as granite. The only rock that granite forms is the metamorphic. When granite is subjected to intense heat and pressure it changes into a metamorphic rock called gneiss. Schist is a metamorphic rock that comes in almost infinite variety but its main characteristic is hinted at in its name.

Metamorphic rock any rock that results from the alteration of preexisting rocks in response to changing conditions such as variations in temperature pressure and mechanical stress and the addition or subtraction of chemical components. Gneissgranite gneiss is a metamorphic rock formed from granite gneiss schist quartzite. The view shown in the photo is about 12 inches across.