Earth Science Essay Example For Students

Earth Science Essay The 8 most common elements in the earths crust are Oxygen, Silicon, Aluminum, Iron, Calcium, Sodium, Potassium, ; Magnesium. They compose 98.5% of the total crust. A mineral occurs naturally, is a soli, inorganic, has chemical composition and a crystalline structure. Native minerals are single elements. Compounds are 2 or more. There are more compound than native. You can identify minerals by color, streak, luster, hardness, cleavage, and fracture. Minerals form by magma erupting and forming lava then cooling. They can also form by evaporation of water containing dissolved ions. Silicates are the most common group of minerals found in the earths crust. The structure of minerals are orderly. They form crystalline. A crystalline has flat faces and smooth surfaces. Igneous rocks are formed from magma. If they are intrusive (plutonic), they have large crystals and cooled slowly. If they are extrusive, they cool quickly, have fined grain. 9) Gabbro is also a mafic rock and phaneritic, consist of mosaic of large, macroscopic crystals, shiny luster and rough surfaces. It is formed by slow crystallization of magma at considerable depth below the surface. 10) Felsite (rhyolite) is felsic and aphanitic, is made of mosaic of microscopic crystals, dull luster and smoother surfaces. Formed from rapid crystallization of magma, at or near the surface or in chilled margins. 11) Granite is a felsic rock which is phaneritic, it is mosaic of large, macroscopic crystals, shiny luster, and rough surfaces. It is formed by slow crystallization of magma, at a considerable depth below the surface. 12) Felsite Porphyry is a felsic/intermediate rock which is aphanitic porphyritic, it has large crystals embedded in aphanitic matrix. It is formed by two-stage crystallization, first slow crystallization, then rapied crystallization near the surface. 13) Basalt Porphyry is a mafic rock and is aphanitic porphyritic, it has large crystals embedded in aphanitic matrix and is formed in two-stage crystallization, first slow crystallization, then rapid crystallization near the surface. III. The oldest intrusion on the diagram is granite. Granite is a felsic rock which is phaneritic, it is mosaic of large, macroscopic crystals, shiny luster, and rough surfaces. It is formed by slow crystallization of magma, at a considerable depth below the surface. The type of intrusion here is a batholith which is a large mass of igneous rock that formed when magma was emplaced at depth, crystallized, and subsequently exposed by erosion. The second oldest rock type is basalt. Basalt is a mafic rock and aphanitic, it is mosaic of microscopic crystals, has dull luster and smoother surfaces. Created from rapid crystallization of magma, at or near the surface or in chilled margins. The type of intrusion represented here is a sill. It was formed when magma was injected along sedimentary bedding surfaces. The third oldest is gabbro. ) Gabbro is also a mafic rock and phaneritic, it consist of mosaic of large, macroscopic crystals, shiny luster and rough surfaces. It is formed by slow crystallization of magma at considerable depth below the surface. The type of intrusion represented here is a laccolith, which is a massive ingneous body intruded between preexisting strata. The youngest is felsite porphyry. Felsite Porphyry is a felsic/intermediate rock which is aphanitic porphyritic, it has large crystals embedded in aphanitic matrix. It is formed by two-stage crystallization, first slow crystallization, then rapid crystallization near the surface. This type of intrusion is called a dike. It was produced when magma was injected into fractures that cut across rock layers .