Civil Engineering - Building Materials - Discussion

Metamorphic rocks formed from the transformation of existing rock types by a process called metamorphism. Metamorphic rocks make form 12% of the Earth's land surface.

Common examples of metamorphic rocks are quartzite, gneiss, slate, schist, marble, etc.

Marble is a metamorphic rock formed from limestone.
Slate is a metamorphic rock formed from shale and mudstone.
Gneiss is a metamorphic rock formed from granite.
Graphite is a metamorphic rock formed from coal.

Gneiss is a rock with higher crushing strength and basically having good mechanical properties in comparison to other metamorphic rock. So it is obtained from metamorphic action over granite and granite is igneous rock.

Rocks come from metamorphic action of sedimentary rocks are weak in mechanical properties in comparison to comes from metamorphic action of igneous rock.

Gneiss is a metamorphic rock. Gneiss is formed by high temperature and high-pressure metamorphic processes acting on formations composed of igneous or sedimentary rocks. Orthogneiss is gneiss derived from igneous rock (such as granite). Paragneiss is gneiss derived from sedimentary rock (such as sandstone).

So, the Answer is: metamorphic.

Gneiss is metamorphic rock. How come a metamorphic rock obtained from metamorphic rock only?

Gneiss is absolutely metamorphic rock obtained from granite which is an igneous rock. Gneiss sometimes also has its parent rock as shale which is a sedimentary rock. So the answer must be igneous -sedimentary rock or simply igneous rock.

Gneiss is a high grade metamorphic rock, meaning that it has been subjected to higher temperatures and pressures than schist. It is formed by the metamorphosis of a granite, or sedimentary rock.

Gneiss displays distinct foliation, representing alternating layers composed of different minerals.

Gneiss is a high-grade metamorphic rock, meaning that it has been subjected to higher temperatures and pressures than schist. It is formed by the metamorphosis of granite, or sedimentary rock. Gneiss displays distinct foliation, representing alternating layers composed of different minerals.

Gneiss is a high-grade metamorphic rock, meaning that it has been subjected to higher temperatures and pressures than schist. It is formed by the metamorphosis of granite or sedimentary rock. Gneiss displays distinct foliation, representing alternating layers composed of different minerals.

Gneiss, a metamorphic rock that has a distinct banding, which is apparent in hand specimens or on a microscopic scale. Gneiss is usually distinguished from schist by its foliation and schistosity; gneiss displays a well-developed foliation and a poorly developed schistosity and cleavage.

Gneiss is formed by high-temperature and high-pressure metamorphic processes acting on formations composed of igneous or sedimentary rocks. Orthogneiss is gneiss derived from igneous rock (such as granite). Paragneiss is gneiss derived from sedimentary rock (such as sandstone).

Gneiss is formed by high-temperature and high-pressure metamorphic processes acting on formations composed of igneous or sedimentary rocks. Orthogneiss is gneiss derived from igneous rock (such as granite). Paragneiss is gneiss derived from sedimentary rock (such as sandstone).