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Published byJacob Floyd Modified over 9 years ago
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Be sure to get your daily dose.
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They occur naturally in the Earth’s crust. They are inorganic. They are solid. They possess a definite chemical structure. Rocks are simply aggregates of two or more minerals. There exist roughly 4000 known minerals. Most minerals are comprised of two or more elements.
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Atoms are the smallest particle that has all the characteristics of an element. Atoms are made of subatomic particles. Protons – found in nucleus, 1 AMU, (+) Neutrons – found in nucleus, 1 AMU, neutral Electrons – orbiting nucleus, 1/1836 AMU, (-) Ions have gained or lost electrons Isotopes carry varying number of neutrons.
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Crystal form – the external expression of the internal orderly arrangement of atoms. Without space limitations, crystals are readily apparent. (example – Quartz)
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When space is limited, crystalline form is not readily apparent and takes on a different appearance. (example – Granite)
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Luster describes the appearance or quality of light reflected from the surface of a mineral. Luster is described as metallic or non-metallic. Metallic – (example Pyrite, eg: “Fool’s Gold”)
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Non-metallic minerals are described as: Vitreous (glassy, example – Quartz, used in jewelry and time-keeping) Pearly (example – Muskovite, used in jewelry, clothing accessories, and cosmetics)
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Silky (example – Calcite, used in cosmetics) Resinous (example – Amber, used in jewelry)
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Earthy (dull, example – Chrysocolla, used in jewelry and cosmetics)
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Color is an unreliable way of classifying to the untrained eye. Some minerals may exhibit varying colors depending on concentration of elements. (example – Quartz)
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Streak is the color of a mineral in its powdered form. This indicator is much more reliable than “color”. Streak is obtained by rubbing the mineral across a piece of hard, unglazed porcelain.
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Mineral hardness is measured on a Mohs scale. The scale uses known and well-established standards of hardness and a comparison is drawn using the sample.
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Because some bonds in crystals are weaker than other bonds, minerals can be broken (cleaved) along planes formed by these weak bonds. Not all minerals are prone to cleavage. Those that are break in such a way that they can be readily identified.
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Minerals can break in ways other than along planes caused by weak bonds. These breaks are known as “fractures”. These fractures can be curved (glass) or splintered (asbestos). Most fractures in minerals are irregular.
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Comparison between the density of a mineral to the density of fresh water. If the density of a mineral is twice that of fresh water, the specific gravity of that mineral is 2.
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Of more than 4000 minerals identified, no more than a few dozen are considered abundant. In fact, only 8 elements compose the bulk of these minerals and account for more than 98% (by weight) of the Earth’s crust. The minerals are called “rock- forming”.
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Silicates – comprised of combinations of Silicon and Oxygen atoms. This group is the most common mineral group. Other than a few “pure” silicates (like quartz), silicates are electrically neutral. Uses include lenses, gauges, adhesives, and many manufacturing processes.
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Carbonates – comprised of combinations of Carbon and Oxygen atoms. These rock-forming minerals make up about ¼ of the Earth’s crust. But, they are economically important. Calcite makes up the bulk of carbonates and is the basis for rocks like limestone and marble. Halite (table salt) and Gypsum (used in wallboard) are two common carbonates.
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Reserves are identified deposits from which minerals can be profitably extracted. Ores are useful metallic minerals that can be profitably extracted. Non-metallic minerals used as building materials, abrasives, fertilizers, etc. are identified as industrial rocks and minerals. Although these minerals occur naturally, they are typically not economically feasible as a resource unless they are refined (concentrated).
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Mining is used to extract minerals from the Earth’s crust. Shaft, Slope, Drift, and Open-Pit mines have been used to obtain minerals.
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Bingham Canyon Copper Mine, near Salt Lake City, UT. Over 2.5 miles across and almost 1 mile deep.
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Historically, machinery was on a “human scale”.
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Draglines are used to remove ore from the mine floor.
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Trucks used to move mined ore to surface.
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