Composition Of Granite Gneiss

Composition and texture of gneiss although gneiss is not defined by its composition most specimens have bands of feldspar and quartz grains in an interlocking texture.

Composition of granite gneiss.

Ortho gneiss is essentially metamorphosed granite so it too is similar in appearance to granite. Gneiss usually is distinguished from schist by its foliation and schistosity. Rocks are naturally occurring solid masses or aggregates of minerals. It was originally a mining term meaning a country rock in the ore mountains erzgebirge which contained metalliferous veins.

Chemical composition of gneiss gneissic rocks are usually medium to coarse foliated. For the casual student it is convenient to think of a gneiss as a rock with parallel somewhat irregular. This is a rock that is formed from pre existing igneous rocks such as granite that have been subject to conditions of high pressure and temperature. There are three major types of rocks as sedimentary rocks igneous rocks and metamorphic rocks.

It is a step above gneiss in the metamorphic process meaning schist has been subjected to less intense heat and pressure. Pink k feldspar gray quartz and black biotite. Schist is a metamorphic rock usually formed originally from shale. Paragneiss is gneiss derived from sedimentary rock such as sandstone.

The term gneiss was brought to scientific usage from the german language. Gneisses which can be metamorphosed igneous rocks or their equivalent are termed granite gneisses diorite gneisses and so on. Gneiss is formed by high temperature and high pressure metamorphic processes acting on formations composed of igneous or sedimentary rocks. In fact primary gneiss is largely indistinguishable from granite at aerial photograph scales.

These bands are usually light in color and alternate with bands of darker colored minerals with platy or elongate habits. Gneiss is a hard rock that has a mineral composition similar to granite as it contains the feldspar mica and quartz. Gneiss forms at higher temperatures and pressures than schist. The main difference between gneiss and granite is that gneiss is a type of metamorphic rock whereas granite is a type of igneous rock.

Gneiss metamorphic rock that has a distinct banding which is apparent in hand specimen or on a microscopic scale. Gneiss is made up of coarse grained minerals such as quartz and feldspar. Gneiss is a high grade metamorphic rock having many of the aerial photograph characteristics of granite. This specimen has a composition of an ordinary granite.

Orthogneiss is gneiss derived from igneous rock such as granite. Granitic gneiss has a mineral composition similar to that of granite. Gneiss displays a well developed foliation and a poorly developed schistosity and cleavage.