Minerals are classified by their chemical composition as Silicates, Phosphorites, carbonates, and halides are all major mineral groups.
Silicates contain silicon (Si) and oxygen (O), the two most abundant elements in the earth and comprise the majority of Earth's crust. They have a chemical formula SiO2. Common silicate minerals include olivine, pyroxene, amphibole, mica and quartz.
Phosphorites are sedimentary rocks of biochemical origin and are rich in phosphate with chemical formula PO4. They are mostly used as chemical fertilizers. They are also used as food preservatives, anti-corrosion agent and also in the field of metallurgy. Limestone and mudstone are common phosphate bearing rocks.Carbonates are the minerals mostly found in the Earth’s near surface crust. They have the chemical formula CO3 and usually occur in combination with calcium, sodium, Barium and Iron. Calcite is one of the best known carbonate.
Salts or Halides form from halogen elements. Some of the common halogen elements are chlorine and iodine. They are dissolvable in water and have a very soft texture. Halite or table salt is a common example. Its chemical formula is NaCl.
Define batholith, dike, laccoliths, pluton, sill, intrusive, and extrusive.
Batholiths: Batholiths are large bodies of rocks made of molten magma that has solidified below the earth's surface. They are mostly composed of rock types such as granite.
Dike: Dike is a flat body of sedimentary rock that traverses through another type of rock. It is formed in open spaces between rocks.
Laccoliths: Laccoliths are mushroom-shaped bodies with a flat floor and a domed roof. They are formed by the intrusion occurs between 2 layers of sedimentary rocks.
Pluton: Plutons are steep, pointed peaks formed due to molten magma under the Earth's crust. Most of the plutons are not visible as they lie deep inside the Earth's crust. Only a few of them which have been formed due to the collision between tectonic plates can be seen above the surface of the Earth.
Sill: Sill is formed when magma is pushed between the rock layers. It forms a horizontal sheet of igneous rock and looks like a tabular body.
Intrusive and extrusive: Intrusive refers to the mode of formation igneous rock that has solidified from magma within the Earth’s crust. In intrusive, the lava explosions take place inside the Earth’s crust and lava is barely seen to flow above the surface of the earth. Whereas, in extrusive, hot magma from inside flows out of the earth’s surface or explodes violently into the atmosphere.
Define caldera, flood basalt, pyroclastic rock, shield volcano, and phreatic eruption.
Caldera: A large, basin-like depression resulting from the explosion of a volcano or the collapse of the center is known as Caldera. Calderas are typically much wider in diameter.
Flood basalt: Flood basalt eruptions are a type of volcanic activity which occurs for a long period of time and over a large area. They can occur on land or on the ocean floor.
Pyroclastic rocks: Pyroclastic rocks are rocks formed by accumulation of material generated by explosive fragmentation of magma during volcanic eruption. The fragments are from older rocks or from solidified lava fragments.
Shield volcano: A shield volcano is a wide volcano with shallowly-sloping sides and is usually surrounded by gently sloping hills. Shield volcanoes are formed by lava which flows slowly out of the earth’s surface.
Phreatic eruption: Phreatic eruptions are caused when magma comes in contact with the ground water. In this type of eruptions, the steam which is generated cannot with stand the pressure inside the earth and bursts out above the surface of the earth.
Define bedding, evaporite, fossil, strata, and detrital sediment.
Bedding: Bedding is the area of separation between rock strata made by cross deposition of sediments. They are originally in line with the horizon and look like sloppy layers.
Evaporites: Evaporites are a group of rocks which are formed when the sea water evaporates and the minerals present in the vapor precipitate into a solid substance. Rock salt is one of the most common examples.
Fossil: Fossils are physical evidence of preexisting organisms, either plant or animal. These include skeletal remains of animals, leaf impressions, tracks and trails, burrows, droppings, and root casts.
Strata: Strata are bed of sedimentary rocks, generally consisting of one kind of matter representing continuous deposition.
Detrital sediment: Detrital sediments form when buried mineral or rock fragments are compacted and cemented. Sandstone is an example.
Define regional metamorphism, shock metamorphism, contact metamorphism, and burial metamorphism
Regional metamorphism: Whenever tectonic plates collide with each other, the composition and appearance of the rocks change over a wide area due to the heat and force involved during the collision. This type of metamorphism is referred to as regional metamorphism and is generally seen in rocks of mountain belts or eroded mountain ranges.
Shock Metamorphism: When there is a very large volcanic explosion, ultrahigh pressures can be generated in the effected rock. This high pressure can produce stable components such as silicon dioxide. It also results in the production of textures called shock lamella which look like thin plates. This phenomenon is called as Shock Metamorphism.
Contact metamorphism: Contact metamorphism occurs in intrusive rocks at high temperatures and low pressures as the magma comes in contact with the adjacent rocks. The rock thus produced looks like a fine grain.
Burial metamorphism: Inside the earth’s crust, at a depth of several hundred meters, temperatures can rise to as high as 300oC and above. At this extreme temperature, new minerals grow, but the original rock does not look like it is metamorphosed. One such example of a mineral produced thus is Zeolite.
