These are photomicrographs - very thin slices of rock, seen in … Foliated textures produced by shearing and breaking, such as in a fault zone or a meteor impact crater, are referred to as mylonitic. The rock has split from bedrock along this foliation plane, and you can see that other weaknesses are present in the same … The gray color is a distinctive shade, often called “slate.”. wikiHow, Inc. is the copyright holder of this image under U.S. and international copyright laws. The first step involves determining the texture of your unknown rock sample. Other kinds of metamorphic rock are named for the kinds of minerals present, the size of the grains and other textures. When you split a rock into very small pieces, the pieces are different from each other. This image is not<\/b> licensed under the Creative Commons license applied to text content and some other images posted to the wikiHow website. Shale. Heat from the intrusion of a dike or sill or flow can bake the adjoining rocks in a contact metamorphic zone. GEO. Figure 7.7 shows an example of this effect. Metamorphic rock is classified by texture and composition. wikiHow, Inc. is the copyright holder of this image under U.S. and international copyright laws. Thanks to all authors for creating a page that has been read 3,701 times. Now, they're not parents like your mom and dad, but they do come from parent rocks. Shale The rock that is quickly transforming the energy industry. We know ads can be annoying, but they’re what allow us to make all of wikiHow available for free. We use cookies to make wikiHow great. Not all metamorphic rocks have luster or shiny grains. The mineral composition of the rock can be determined based on observations with a hand lens and if needed, physical or chemical tests. The pre-existing rock is called either the parent rock or the protolith. They are not made from molten rock – rocks that do melt form igneous rocks instead. Although different rocks can contain the same minerals, they are classified on how they were formed, and as we know metamorphic rocks from when they are exposed to heat and pressure deep in the Earth’s surface. We’d love your input. The color alone can’t be used to distinguish the two, but it can help improve your confidence in the analysis. Determining Whether a Rock is Metamorphic 1 Hold the rock to the light and see if it has a shine or shimmer. This image is not<\/b> licensed under the Creative Commons license applied to text content and some other images posted to the wikiHow website. Include your email address to get a message when this question is answered. Those formed as a result of widely distributed pressure and temperature changes induced by tectonic movements are known as regional metamorphic rocks. Metamorphic Rocks: Metamorphic Rock Identification. Did you have an idea for improving this content? This image is not<\/b> licensed under the Creative Commons license applied to text content and some other images posted to the wikiHow website. Metamorphic rocks tend to have more luster than igneous or sedimentary rock. You only need to streak the rock against roughly 2 millimetres (0.079 in) of glass. Heat from the intrusion of a large igneous mass can metamorphose a large area. OTHER SETS BY THIS CREATOR. Geology rock and mineral identification. Metamorphism also happens when rocks are buried deeply during the process of mountain building… 86 terms. 70 terms. Knowing the parent rock helps us classify these rocks, and we can further classif… Many rocks used in architecture and design are metamorphic, like slate and marble. ENV GEOLOGY TEST 2. The rock also has a strong slaty foliation, which is horizontal in this view, and has developed because the rock was being squeezed during metamorphism. The classification of metamorphic rocks is based on the minerals that are present and the temperature and pressure at which these minerals form. Metamorphic rocks arise from the transformation of existing rock types, in a process called metamorphism, which means "change in form". Licenses and Attributions During this long process of change, new minerals grow from the chemicals in the old rocks, forming new rocks. For example, when you break granite apart, you get small pieces of quartz (clear), feldspar (pink or white), and mica (black). Did you know that metamorphic rocks have parents? Rocks are made of minerals. Metamorphic rocks (changed rocks) are made when existing rocks are subjected to high temperatures and high pressures for long periods of time. For example, mica schist has very thin layers of mica, and garnet gneiss (pronounced like nice) has garnet crystals in thick layers of quartz and feldspar. Examples of complete descriptions of nonfoliated metamorphic rocks include nonfoliated, medium grained for quartzite, or nonfoliated, coarse grained for marble. Metamorphic Rocks: Igneous, sedimentary, and metamorphic rocks are the three types of rocks that are found on Earth. Metamorphic rocks are the third great class of rocks. Stretched and welded cobbles and pebbles – Fractures through grains, not around them as in rougher conglomerate, Composed of rock fragments, quartz, chert, Welded sand grains – Fractures through grains, not around them as in rougher sandstone, http://cc.pima.edu/~lumen/glg101/module%20parts%20-%20LUMEN/Module8/L_Assign8_LabInfo.html, https://open.umn.edu/opentextbooks/BookDetail.aspx?bookId=506, thick layers of quartz, feldspar, and mica, sugary to course crystals, fizzes in HCl acid, dense, black, fine grained, flint-like fracture, Very, very thin, irregular layers of mica, Thin, irregular layers of mica & platy minerals, Thin, irregular layers of mica and platy minerals, Thick bands, wavy, semi-continuous layers of white quartz, feldspar, and mica. Physical Geology, Adapted by Anne Huth, Pima Community College. Igneous. Metamorphic rocks started out as some other type of rock, but have been substantially changed from their original igneous, sedimentary, or earlier metamorphic form. This image is not<\/b> licensed under the Creative Commons license applied to text content and some other images posted to the wikiHow website. Read the descriptions in your lab manual or textbook for the source rock of each of the metamorphic rocks that you identify. This video discusses how to identify a metamorphic rocks: Contribute! wikiHow, Inc. is the copyright holder of this image under U.S. and international copyright laws. Essentially, picture a rock that is made of silly putty. Extreme pressure or heat can squeeze or cook rocks so much that they change their character, turning into metamorphic rocks. As with igneous and sedimentary rocks, metamorphic rocks are classified on the basis of texture (grain size, shape, orientation) and mineral composition.However, the classifiction of metamorphic rocks is more difficult to get into than with igneous and sedimentary rocks, for a couple of reasons. This alignment may be displayed as parallel planes along which the rock splits, by overlapping sheets of platy minerals such as micas, by the parallel alignment of elongate minerals such as amphiboles, or by alternating layers of light and dark minerals. This image is not<\/b> licensed under the Creative Commons license applied to text content and some other images posted to the wikiHow website. References. Metamorphic rocks (changed rocks) are made when existing rocks are subjected to high temperatures and high pressures for long periods of time. This image is not<\/b> licensed under the Creative Commons license applied to text content and some other images posted to the wikiHow website. As a result, nonfoliated rocks commonly appear massive and structureless, with only a few lines of impurities through the rock. This image may not be used by other entities without the express written consent of wikiHow, Inc.
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