This essay Rock Classification has a total of 700 words and 3 pages.
October 11, 1999
Rocks are classified to make it easier on people to identify them in the future. This can be done by a numerous amount of ways. Each rock type has their own specific ways, but there are two distinct characteristics that apply to all. These are texture and composition. These two, along with many others helps to classify igneous, sedimentary, and metamorphic rocks.
Igneous rocks are classified first by texture. This is broken down mainly into grain size. First there are intrusive, or plutonic igneous rocks. These types of rocks cool within the crust and forms large, visible crystals. The opposite would be extrusive, or volcanic rocks. These cool at the surface rapidly, forming small grains. A combination of the two would be porphyritic, large grains in an aphanitic, or extrusive matrix. Secondly, composition is used to classify igneous rocks. There are four types, ultramafic, mafic, intermediate, and felsic. Ultramafic rocks are very dark and contain and extreme amount of iron and magnesium. Mafic rocks are also dark in color; they too contain high iron and magnesium amounts. An example would be olivine, or pyroxene. Intermediate igneous rocks are made from silica and plagioclase. They tend to be grays and browns in color. Finally, felsic socks are light in color and contains high amounts of silica. Quartz and potassium feldspar are examples of felsic igneous rocks. Other types of rocks are classified similarly.
Sedimentary rocks form from the weathering of pre-existing rocks. The broken down particles are then compacted and cemented together after the sorting process is complete. Depending on what the sedimentary rock is formed by, determines whether is known as clastic or chemical. Clastic rocks are composed of particles from weathering. They are then sorted by grain size, gravel being the largest and clay being the smallest. A few examples would be sandstones and shales. Chemical sedimentary rocks are biochemical, and contain ions in the solution from weathering. These are also further classified. First you have limestone, which can be either organic or inorganic. An example would be fossiliferous or chalk. Next is dolostone, and it is formed from dolomite. Chert is next; and can be organic or inorganic also. Flint and jasper are some examples of chert. Rock salt and gypsum are what are known as evaporites. These form from the evaporation of saline waters in an arid environment. Finally there is coal, which is organic and forms from buried plant remains and carbon. There is one more type of rock that is classified the same way as the previous two.
Metamorphic rocks are pre-existing rocks that are changed by heat and pressure. The pre-existing rock is called the parent rock, or protolith. Metamorphism occurs in these rocks when the minerals become instable. There are two types of metamorphism, contact and regional. Contact is high temperature, low pressure. It is basically a massive rock that is baked. Regional is high pressure and low temperature. Strong fabric, or layering, develops from this kind of metamorphism. Along with metamorphism, you get texture changes. The first is recrystallization, which is where you get new minerals from old. Some of the new minerals that form are micas, feldspars, and garnet. You can also get foliation, which is a planar fabric in a metamorphic rock. Simply, this is the alignment of minerals within the rock that are platy. Types of foliation are slaty cleavage, schistosity, and gneissic layering. Non-foliated rocks can also form. These are massive in size, uniform, and have no planar fabric. Marble and quartzite are the two best examples of a non-foliated metamorphic rock.
In conclusion, classification of rocks is a very important and difficult process. If rocks were not classified, then no one would know what rock was what, and that would end in chaos. All three families of rocks, igneous, sedimentary, and metamorphic are all classified mainly by texture and composition. Each family has different ways and names for this process, but it basically the same thing. All in all, classification of rocks comes down to the texture is contains, whether it has large, visible grains or small grains, and what the rock itself is comprised of.
Topics Related to Rock Classification
Metamorphic rocks, Petrology, Metamorphic petrology, Igneous petrology, Volcanology, Igneous rock, Foliation, Felsic, Sedimentary rock, Schist, Metamorphism, Ultramafic rock
Essays Related to Rock Classification
Rock ClassificationRock Classification October 11, 1999 Classifying RocksRocks are classified to make it easier on people to identify them in the future. This can be done by a numerous amount of ways. Each rock type has their own specific ways, but there are two distinct characteristics that apply to all. These are texture and composition. These two, along with many others helps to classify igneous, sedimentary, and metamorphicrocks. Igneous rocks are classified first by texture. This is broken down mainly into
Volcano Mount VesuviusVolcano Mount Vesuvius Mount Vesuvius is a volcano located in southern Italy, near the bay of Naples and the city of Naples. It is the only active volcano on the European mainland. Vesuvius rises to a height of 1277 m (4190 ft). Vesuvio (Vesuvius) is probably the most famous volcano on earth, and is one of the most dangerous. Mount Vesuvius is a strato-volcano consisting of a volcanic cone (Gran Cono) that was built within a summit caldera (Mount Somma). The Somma-Vesuvius complex has formed ove
WetlandsWetlands Soil and land managment Soil and Land Management The soil triangle is graph that helps the person determine the type of soil they are testing. This type of graph being a triangle has three sides. The first side, or right side is the percent of silt found in the soil sample. The second side, or the bottom is the percent of sand found in the soil sample. The third side, or the right side is the percent of clay found in the soil sample. You read the graph from right to left being silt, san
Copper and Molybdenum Deposits in the United StateCopper and Molybdenum Deposits in the United States Copper and molybdenum resources were not recognized as valuable commodities until economic needs demanded the collection and processing of these minerals in large amounts. The most expansive deposits of copper and molybdenum occur in massive low grade ores and are found in intrusive porphyry formations, although many smaller sized but higher grade ores are located in non-porphyry areas. The nation has abundant domestic copper ore reserves but b
Industry ProductionIndustry Production The structure of industrial production and the service industries is characterized by the prevalence of smarkforce, 30% beingll and medium-sized companies (94% and 5.6% according to 100 workers) thoug981 data), employing, however, only 70% of the workforce, 30% being monopolized by large c ompanies (more than 100 workers) though these comprise only 0.4% of the total. This means that companies are widely dispersed over the whole country, obviously with significant location and
CanadaCanada Canada, is the world\'s second largest country and it is the largest country in the Western Hemisphere. It comprises all of the North American continent north of the United States, with the exclusion of Alaska, Greenland, and the tiny French islands of St. Pierre and Miquelon. Its most easterly point is Cape Spear, Newfoundland and its western limit is Mount St. Elias in the Yukon Territory, near the Alaskan border. The southernmost point is Middle Island, in Lake Erie and the northern ti
Industry and the effects of climate in ItalyIndustry and the effects of climate in Italy Industry The structure of industrial production and the service industries is characterized by the prevalence of smarkforce, 30% beingll and medium-sized companies (94% and 5.6% according to 100 workers) thoug981 data), employing, however, only 70% of the workforce, 30% being monopolized by large c ompanies (more than 100 workers) though these comprise only 0.4% of the total. This means that companies are widely dispersed over the whole country, obvio
The Physical and Economic Geography Of CanadaThe Physical and Economic Geography Of Canada CANADA Canada, is the worldıs second largest country and it is the largest country in the Western Hemisphere. It comprises all of the North American continent north of the United States, with the exclusion of Alaska, Greenland, and the tiny French islands of St. Pierre and Miquelon. Its most easterly point is Cape Spear, Newfoundland and its western limit is Mount St. Elias in the Yukon Territory, near the Alaskan border. The southernmost point is Mi
BIG unit assignmentBIG unit assignment D: Sedimentary rocks and processes: o How does each of the following types of sedimentary rocks form? Clastic rocks: are formed by broken fragments of pre-existing rocks and minerals. Chemical rocks: are precipitated from solution, from evaporation. o Describe the distinguishing features of and identify the following as to which type of sedimentary rocks they are (make a table): Conglomerate A sedimentary rock containing abundant, rounded pebble, cobble, and boulder-sized par
Massachusetts ROCKS!Massachusetts ROCKS! APES F Geology 120,000 years ago ice began to form at a rapid pace in northern Canada(Grette, www.biomass.umass.edu). This sheet quickly (on a geologic scale) swept down the eastern seaboard and engulfed the northeast down to present day Long Island, New York in a sheet of solid ice. This icesheet later in history became known as the Laurentide icesheet, named after the region in Canada in which it made its descent(Oldale, http://pubs.usgs.gov). Little did anything know b
DiamondsDiamonds Introduction The first diamonds were probably discovered in India, in around 800 B.C. The volcanic source of these diamonds was never discovered, but the alluvial deposits were rich enough to supply most of the world\'s diamonds until the 18th century, when dwindling Indian supplies probably spurred the exploration that led to the discovery of diamonds in Brazil, which became the next important diamond source. Beginning in l866, South Africa\'s massive diamond deposits were discovered,
The EmeraldThe Emerald your name date class period teacher name The Emerald The Emerald is the gemstone that represents the month of May. A gemstone is the naturally occurring crystalline form of a mineral which is desirable for its beauty, valuable in its rarity, and durable enough to be enjoyed for generations. There are more than 30 popular gems and many more rare collector gemstones. The Emerald is considered the gem of eternal spring because of its green color. The ancients prized it as the gemstone
Science NotesScience Notes Notes on the lithosphere- (rock sphere) Upper most part is crust of earth. Compiled of rocks of outer crust. Outermost shell. Upper part- rocks we see at and near the earths surface. Crust is 5 to 10 km thick under most oceans and 24 to 60 km thick under the continents. The lithosphere under the crust is solid, dense material. (more dense than surface materials). Lithosphere 100-200 km. Notes on the aesthenosphere- zone beneath the lithosphere. Thick like tar. Weak because of high
Formations of things Formations of things Restless earth How earthquakes are formed at destructive plate margins? Two plates move towards each other. One is made from oceanic crust and one of continental crust. The oceanic plate is denser than the continental. It sinks beneath the continental plate - which is subduction. This exerts great pressure on the crust and the release of the pressure that has built up over time causes the plates to shift and results in an earthquake. Diagram should show oceanic and continen