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Minerals and Resources. Minerals Versus Rocks Mineral - any naturally formed, solid chemical element or compound that has a definite composition and crystalline.

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Presentation on theme: "Minerals and Resources. Minerals Versus Rocks Mineral - any naturally formed, solid chemical element or compound that has a definite composition and crystalline."— Presentation transcript:

1 Minerals and Resources

2 Minerals Versus Rocks Mineral - any naturally formed, solid chemical element or compound that has a definite composition and crystalline structure Rock - any natural, solid aggregate material, usually made of minerals All minerals are rocks, but not all rocks are made of minerals Quartz Granite

3 Mineral Properties Chemical composition Crystalline shape Hardness Color Streak Luster Cleavage Fracture Specific Gravity Magnetism These properties are used to identify different minerals

4 Chemical Composition Extremely important for the minerals industry. Often want an element or compound in mineral, and not necessarily the mineral itself Ex.: iron and sulfur from iron pyrite (FeS 2 ) Identifying a mineral by chemical composition requires submitting a sample for chemical analysis; can be time consuming and expensive

5 Crystalline Shape Useful for identification; of little use for industry, as crystalline shape can be replicated in lab Jewelry about the only use for this property; even then, the fact that crystals can be artificially created means that their value is artificial, as well Shape normally determined by chemical formula Hope Diamond

6 Hardness 1 = Talc 2 = Gypsum 3 = Calcite 4 = Fluorite 5 = Apatite 6 = Orthoclase 7 = Quartz 8 = Topaz 9 = Corundum 10 = Diamond Mho’s Scale Relative scale based upon what mineral will scratch what mineral Ex. Orthoclase will scratch apatite, but quartz will scratch orthoclase Fingernail is about a 2.5; steel nail = 5.5 Diamond is hardest, which means that it does have some industrial application Hardness does not relate to elemental scarcity or value

7 Color and Streak Color - what color unmolested mineral appears to be Streak - color of ground mineral These two can be radically different. Ex.: Iron pyrite color is gold (fool’s gold); streak is black Hematite is black/gray; streak is red-brown Color is unreliable as identifier since impurities can change it; streak is more reliable

8 Other Properties Depending upon mineral, will use a variety of other identifiers Magnetism - used to identify iron ores Cleavage - used to identify minerals like mica and gypsum that form crystals that loosely bond together Fracture - helps to identify minerals with crystalline shapes that do not cleave

9 Mineral Types Silicates (feldspars, garnets, micas, olivine, quartz, clay minerals) Native Elements (diamond, sulfur, gold) Sulfides (galena, pyrite, millerite, sphalerite) Sulfates (barite, celestite, gypsum, secondary sulfates) Oxides (goethite, hematite, ilmenite, limonite, uranium minerals) Carbonates (calcite, dolomite, other iron-carbonate and others) Phosphates (apatite, vivianite, pyromorphite) Halides (fluorite, halite) Based upon the key elements in the chemical composition, minerals are grouped into subcategories

10 Silicates The largest group of minerals (30% of all minerals; 90% of whole crust); defined by having SiO 4 tetrahedra Includes some gemstones such as tourmaline and topaz Also has useful minerals such as talc, kaolin, and mica Rocks made from silicates very useful for road and building materials

11 Native Elements Contains all of the metals (gold, silver, copper, etc.) and metal alloys Also includes diamonds and graphite (carbon) Rare to find elements in their natural state; oftentimes, a primary method of metal extractions is from some other class Ex. Copper and lead from sulfide minerals

12 Strategic Resources Defn. - resources that a country uses, but cannot produce enough to meet demand If cannot guarantee supply, economy could be hurt if supplies cut; Ex. OPEC oil embargo of 1973 Wealthy nations try to stockpile surplus to act as buffer against outside forces affecting economy

13 Mining Vulcan Materials pit mine, Kennesaw, GA, 1993 Hollywood image of old man with mule, pick axe, and dynamite all but disappeared Most economic mining done on huge scale with big equipment Open pit - dig deep into the ground, exposing new rock to surface Stripmining - shallow mine over large area Underground mining - tunnels

14 Open Pit Mineral ore dug from deep hole created in the surface. Walls of pit have roads built into them for cranes, trucks, etc. to be able to get to bottom Economics of recovery have to constantly be re-evaluated, as hole must get wider as go deeper (walls are the road system)

15 Stripmine Differs from open pit in horizontal extant Stripmines are going after near horizontal seam of materials that are near the surface Overburden is stripped from seam, and then mineral is extracted Once mineral removed, overburden put back on top Federal law now requires remediation

16 Underground Mining Pickaxe and dynamite have been replaced by large tunneling equipment that does the job safer and faster Must leave some pillars of material behind, lest a cave-in ensue Most dangerous form of mining Miner safety in jeopardy from cave-ins and dust (black lung disease)

17 Other Techniques Hydraulic mining - sediments are blasted from hillside with water jets; sediment is sent through sluice boxes; not done much in U.S., but is done many other places (South America) Dredging - similar to hydraulic mining, with the exception being that the sediment is scooped out of the ground instead of being blasted out with water

18 Mining Pollution Superfund Sites Water passing through mine leaches toxic chemicals Tailings piles and ponds erode and contain toxics Processing chemicals are toxic and sometimes released Land slumpage when cave-ins occur Underground fires can burn for decades Many mines are abandoned when economics fail Energy used for entire process is large Pictures from Berkeley Pit in Butte Montana

19 Processing Some rocks and minerals take very little processing Ex: crushed rock for roads and construction material Others take an incredible amount of energy and produce great quantities of waste Smelting - heating metal ores to extreme temperature to release metal; gaseous vapors are toxic and often acidic Leach extraction - pour acid or base on crushed piles of ore, extract metal from leachate by electrolysis; crushed ore is left to contaminate water supply when finished, with acid or base still present

20 Recycling Besides saving environmental damage for extraction and processing, can save huge quantities of energy Recycling aluminum saves 95% Recycling glass saves 25% Recycling steel saves between 60-75% Recycling plastic saves 33% of the energy needed to make them from virgin materials Recycling just one aluminum can will save enough energy to run a 100W lightbulb for 20 hours

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