Mining and Mineral Resources Minerals: solids with characteristic chemical composition, orderly internal structure, and a characteristic set of physical properties -Made up of compounds: atoms of two or more elements chemically bonded together Native element: elements considered to be minerals, eg: gold, silver, copper Ore Minerals • Ore minerals are those that are valuable and economical to extract, such as aluminum, copper, iron, lead, or tin • Gangue minerals are the other minerals that are extracted from rock, and have no commercial value (M)Ore Minerals • Metallic minerals conduct electricity, have shiny surfaces, and are opaque • Nonmetallic minerals are good insulators, may have shiny or dull surfaces, and may allow light to pass through them How do they form? • Hydrothermal solutions are hot, subsurface waters that contain dissolved minerals from the rocks they flow through. New minerals crystallize out of the solutions and fill cracks in the rocks, creating veins • Evaporites form when water contained dissolved salts evaporate, leaving the crystals behind Mineral Resource Uses • Alloys are combinations of two or more metals, like steel or bronze • Other metals can be used without being alloyed • Nonmetals are among the most widely used minerals in the world, such as gypsum, which makes up Sheetrock, or sand and gravel • Gemstones are nonmetallic minerals valued for their beauty, rarity, or durability How to Open a Mine 1. Find a mineral deposit. Use a plane with special instruments on it to find areas with high concentrations of minerals 2. Take samples of rocks from the area 3. Analyze the samples to see what the ore grade, or metal content, is. 4. See if the ore deposit is big enough. 5. Open a mine! $$$$$$$$$$ Types of Mining Subsurface mining is used for ore deposits that are 50 m or more below the Earth’s surface • Room-and-pillar mining is a common method of mining salt and coal • Longwall mining is a more efficient method for mining coal • Solution mining is good for getting soluble minerals like salt or sulfur More Types of Mining Surface mining is used when ore deposits are close to the Earth’s surface • Open-pit mining uses explosives to break up ore, then it is loaded into trucks and taken to processing plants to be removed from the rock • Surface coal mining removes layers of rock called overburden from the top of coal deposits. Loaders remove the coal, then the overburden and soil is replaced. • Quarries are types of open-pit mining where granite and marble are mined Even More Types of Mining • Solar evaporation uses the sun to produce salt – Saltwater is placed in shallow ponds and allowed to evaporate – The salt remaining is harvested and processed for use • Minerals can be concentrated by wind and water into deposits called placer deposits. These can be mined by dredging. He Who Smelt It… • Smelting is the process of removing ore from rock Ore is crushed, then melted Impurities bond with a material called “flux”, and float to the top of the furnace, forming a layer called “slag,” which is removed The purified ore can now be formed into products for use.