The 8 mostcommon elements in the earth’s crust are Oxygen,Silicon, Aluminum, Iron, Calcium, Sodium,Potassium, ; Magnesium.
They compose 98. 5%of the total crust. A mineral occurs naturally, is asoli, inorganic, has chemical composition and acrystalline structure. Native minerals are singleelements. Compounds are 2 or more. There aremore compound than native.
You can identifyminerals by color, streak, luster, hardness,cleavage, and fracture. Minerals form by magmaerupting and forming lava then cooling. They canalso form by evaporation of water containingdissolved ions. Silicates are the most commongroup of minerals found in the earth’s crust. Thestructure of minerals are orderly.
Order nowThey formcrystalline. A crystalline has flat faces and smoothsurfaces. Igneous rocks are formed from magma. If they are intrusive (plutonic), they have largecrystals and cooled slowly. If they are extrusive,they cool quickly, have fined grain. The schemefor igneous rock identification is based on texture,color, composition, and density.
Sedimentaryrocks are the 2nd step in the rock cycle. They arecomposed of bits and pieces of rock that havebeen watered by rain, water, and other things. They compress and cement on top of each otherforming layers. When the water evaporates, thesediments are left behind and forms a new rock.
This rock is either clastic (formed from igneousrock) or organic (formed from living remains). Theother type of sedimentary rock is chemical whichis formed by the evaporation of water and theprecipitation on sediments form a new rock. Metomorphic rock is the recrystalization (changew/o melting) of rocks under extreem heat andpressure. Regional metamorphism occurs overlarge arieas where mountain building has takenplace. Comtact metamorphism occurs whenmolten magma comes into contace w/ souroundingrocks.Category: Science .
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