Q:

What are non-foliated metamorphic rocks?

A:

Quick Answer

Non-foliated metamorphic rocks are rocks that have been changed by heat and pressure into rocks with a non-layered or banded appearance. Some examples of non-foliated metamorphic rocks include quartzite, marble, amphibolite and hornfels.

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Full Answer

Both foliated and non-foliated metamorphic rocks are formed deep under the earth's surface over millions of years by the combination of heat, pressure and chemical processes. The amount of heat and pressure determines the final state of metamorphic rocks, as does their specific mineral contents.

Generally speaking, non-foliated metamorphic rocks were created under extremely high temperatures and very low, even amounts of pressure. These rocks typically cooled very slowly, allowing the minerals within them to form large, uniform crystals that are tightly packed together.

Different types of rocks and minerals can form non-foliated metamorphic rocks. Quartzite is made of metamorphosed sandstone, while marble is formed from limestone that was metamorphosed. Hornfels have no specific composition while amphibolites are formed from hornblende and plagioclase.

Although non-foliated rocks may have small bands of different colors, the crystals that form them generally have no visible organization. On the other hand, foliated metamorphic rocks have very obvious bands of layers that formed as a result of a more rapid cooling or higher pressure. Some examples of foliated metamorphic rocks include gneiss, schist, slate and soapstone.

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Related Questions

  • Q:

    What causes foliation in metamorphic rocks?

    A:

    Pressure that shapes rocks to align in particular directions causes foliation, according to the Mineralogical Society of America. When such differential pressure acts on the forming rocks, it produces layers of rocks that run in parallel to each other, creating the diagnostic banded appearance of foliated rocks.

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  • Q:

    How are metamorphic rocks classified?

    A:

    Metamorphic rocks are primarily classified according to mineral composition and texture, similar to how igneous or sedimentary rocks are classified. However, the forces that form metamorphic rocks, namely pressure, heat and chemically active fluids, can produce a wide range of different substances, which makes classifying these rocks much more difficult.

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  • Q:

    Where are metamorphic rocks found?

    A:

    Metamorphic rocks can commonly be found in mountain ranges, like the Himalayas, Alps and Rocky Mountains. This is because metamorphic rocks form at the core of mountains from the intense pressure and heat. As mountains erode away over time, these types of rocks can be found on the surface.

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  • Q:

    What are metamorphic rocks used for?

    A:

    Metamorphic rocks are used for roofing material, decorative gardening stone, the base for snooker tables, building material, sculpture material and paving material. Metamorphic rocks come in three different types: slate, marble and schist.

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