RocksGroup7

Igneous rocks- and igneous rock are one of the tree main rock types. rock that form when moten cools and crystallizes. facts: make up 90% of the upper part of the earths crust. but their great abundance is hidden on the earth's surface by a relatively thin and widespread layer of sedimentary and metamorphic rocks. classifying igneous rocks. igneous rock are based on mineral compositition, crystal size and texture. differences in magma composition can be observed in the rocks that form when the magma cools and crystallizes. texture is used to subdivided. rock type can be dtermined by estimating the relative percentages of minerals in the rocks. an intrusive igneous rock is when magma rock is underground cools and hardens. rocks that form in this way are called plutonic rcks. many kilometers below the earth surface, molten rock called magma flows into cracks or underground chambers. the magma sits cooling very slowly over thousands of years. as it cools. extrusive igneous rock forms when molten rock eaches the earth's surface and cools. air and moisture cool the lava rapidly. cesiculas is a type of texture when there is a spongy appearance in the rock.

sedimentary rocks-is formed by sedimentation of material at the Earth's surface and within bodies of water. formed by sedimentation of material at the earths surface and within bodies of water. sedimentation is a process that causes minerals and organic particles, being broken down by weather making rocks into small pieces that get carried away and deposited in shallow seas or lakes. the pressure from the wright of the sediments about turns the lower layers to become a solid rock. ex: sandstone- formed in layers. limestone- used in concrete and an excellent building stone. form by fossils. the difference between them is that they form differently. shale- formed from clay. compacted together by pressure. gypsum- made up of sulfate mineral and is formed by evaporating sea water in massive prehistoric basin. they are classified by their texture, may or may not react to acid, has layers, flat or cured layers, composed pieces of cemented of or pressed, if it had pores or not. 3 types of sedimentary rocks- Clastic- the common set of sedimentary rock consist of the granular materials that occur in sediment. sediment mostly consists of quartz and clays that are made by the physical breakdown and chemical alteration of rocks. theses are carried away by water or wind and laid down in a different place. Organic- another type of sediment actually form in the sea as microscopic organism- plankton- build shells out of dissolved calcium carbonate or silica. chemical- theses same ancient shallow seas sometimes allowed large areas to become isolated and begin drying up. they are composed of fragments of pre-existing rocks that have been concentrated, compacted and cemented without necessarily.

metamorphic rock- are formed by existing rocks. is the process of forming metamorphoc rocks within the lithosphere making the rock more dense and less porous. porous- have little spaces in the rock. recrystallization is the process of increasing the size of the mineral crystals and or changing the mineral composition without melting. metamorphic rocks have been modified by heat, pressure and chemical process usually while buried deep below earth's surface. exposure to there extreme conditions has altered the mineralogy, texture and chemical composition of the rocks. there are two basic types of metamorphic rocks. foliated and non foliated. low-grade metamorphism is associated with low temperatures and pressures and ia particular suit of minerals and textures. high-grade- is with high temperatures and pressures and a different suite of mineral textures. intermediate-grade- temperature metamorphism is in between low- and high-grade metamorphism. contact metamorphism- when molten material, such as that in Igneous intrusion, comes in contact with solid rock. REgional metamorphism- when high temperature and pressure affect large regions of earth's crust, they produce. hydrothermal metamorphism- when very hot water reacts with rock and alters its chemical and mineral composition. metallic resources occur mostly in the form f metal ores, although deposits of cure metals are occasionally discovered, many metallic are precipitated from hydrothermal solutions and are either concentrated in veins or spread throughout the rock mass. metamorphism of ultrabasic Igneous rocks produces the minerals talc and asbestos. talc is used as a lubricant, and to provide texture in plants and dusting pattern.

rock cycle- Rock divisions occur in three major families based on how they formed: igneous, sedimentary, and metamorphic. Each group contains a collection of rock types that differ from each other on the basis of the size, shape, and arrangement of mineral grains.The concept of the rock cycle is attributed to James Hutton (1726—1797), the 18th-century founder of modern geology. The rock cycle is a model used to describe the changes to rocks that take place on the earth. These changes show how each type of rock is formed. Some of the processes occur at or near the earth's surface such as weathering, erosion and deposition. Other processes occur deep below the surface such as melting and increased heat and pressure. The Rock Cycle is a group of changes. Igneous rock can change into sedimentary rock or into metamorphic rock. Sedimentary rock can change into metamorphic rock or into igneous rock. Metamorphic rock can change into igneous or sedimentary rock. [| http://www.classzone.com/books/earth_science/terc/content/investigations/es0602/es0602page02.cfm] 