A Metamorphic Rock Formed From Granite

Orthogneiss is gneiss derived from igneous rock such as granite.

A metamorphic rock formed from granite.

Gneissgranite gneiss is a metamorphic rock formed from granite gneiss schist quartzite. Gneiss ˈnaɪs is a common and widely distributed type of metamorphic rock. The end product of their metamorphism is a banded rock with a mineralogical composition like 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.

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. The only rock that granite forms is the metamorphic. 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. Granite gneiss can also form through the metamorphism of sedimentary rocks.

Gneiss is formed by high temperature and high pressure metamorphic processes acting on formations composed of igneous or sedimentary rocks. Slate is another common metamorphic rock that forms from shale. Metamorphic rocks arise from the transformation of existing rock types in a process called metamorphism which means change in form. What rock does granite form from heat and pressure.

Granite is an igneous rock that forms when magma cools relatively slowly underground. Gneissgranite gneiss is a metamorphic rock formed from granite gneiss schist quartzite. The granitic rock in migmatite probably originated from partial melting of some of the metamorphic rock though in some migmatites the granite may have intruded the rock from deeper in the crust. The view shown in the photo is about 12 inches across.

Schist is a metamorphic rock that comes in almost infinite variety but its main characteristic is hinted at in its name. When granite is subjected to intense heat and pressure it changes into a metamorphic rock called gneiss. Schist comes from the ancient greek for split through latin and french. It is usually composed primarily of the minerals quartz feldspar and mica.

Some kinds of metamorphic rocks granite gneiss and biotite schist are two examples are strongly banded or foliated. The preexisting rocks may be igneous sedimentary or other metamorphic rocks. A photograph of polished gneiss from the stock of a countertop vendor.