Economic Uses of Minerals & Rocks - PowerPoint PPT Presentation

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Economic Uses of Minerals & Rocks
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Economic Uses of Minerals & Rocks

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  1. Economic Uses of Minerals & Rocks Energy Resources, Ores, Gems, and Building Materials

  2. Our Earth Resources • Why you must have someone somewhere who develops the resources you use every day:

  3. Our Earth Resources • Resource = • Physical or virtual entity with utility, value, and limited availability • Ore = • Materials that exist in quantities that can be extracted and marketed for a profit • Major types of ores • Metallic (ore mineral) • Nonmetallic (gem, IM) • Energy • Water

  4. Energy Resources: Coal, Petroleum, and Natural Gas • Fossil fuel energy resources are the foundation of technology-based human societies

  5. Oil and Natural Gas Deposits • Origin: • Organic materials trapped in ocean-bottom sediments • Decompose within the rocks and form hydrocarbon liquids (oil and gas) • Hydrocarbons migrate along and within permeable rock layers • Accumulate in an area that is impermeable - "traps

  6. Reservoir rocks are porous and permeable Sandstone, limestone “Unconventional” reservoirs – fractured shales Oil and Natural Gas Deposits in MI

  7. Basic Concepts: Ore Minerals • Resource • Absolute volume of a mineral commodity in existence, independent of economics and technology • Reserves or proven reserves • Known quantity of a resource available (produced at a profit) • Dependant on current economic conditions (including demand) and extant technology • Concentration factor • Ratio of ore material concentration to average crustal concentration • Mode of occurrence • A desirable commodity must occur in a mineral form that is readily processed to produce the commodity • Associated, unwanted mineral material (gangue) and waste after processing (tailings) must be considered in economic assessment

  8. Basic Concepts: Ore Minerals • Ore deposits require • Source for metals (or other elements) • Means of concentrating elements into usable quantities • Types of Ore Deposits • Magmatic (cumulate, lode, pegmatite) • Hydrothermal (porphyry, vein, skarn, exhalative, epigenetic) • Sedimentary (placer, BIF, laterite, evaporite) • Ore Minerals • Native elements (Au, Ag, Cu, Pt, diamond, sulfur) • Sulfides and sulfosalts (pyrite, sphalerite, chalcopyrite, galena) • Oxides and hydroxides (magnetite, chromite, corundum, hematite, rutile)

  9. Directly crystallize from magma – intrusive or extrusive Occur as: Accessory minerals Disseminated deposits Lode deposits Ore in many small veins California gold deposits Pegmatite Felsic plutons; late stage crystallization of magma Rich in incompatible elements: Li, Cs, Be, Sn, & U Cumulates Dense minerals settle out in ultramafic magma chamber Chromite, magnetite, platinum group elements Magmatic Ore Deposits

  10. Hydrothermal Ore Deposits • Involve fluids • Released from crystallizing magma (felsic plutons) • Occur as • Widely disseminated vein networks • Porphyry • Alteration of country rock by late, hydrothermal fluids • Cu, Mo deposited as sulfide minerals in veins • Skarn • Fluid alteration of carbonate country rock during contact metamorphism (metasomatism) • Fe, Pb, Cu, Mo as sulfide or oxide minerals • Epigenetic • Ore bodies not physically associated with the magmatic body that produced the hydrothermal fluids • Pb-Zn and Au-Sb deposits; Upper Mississippi Valley lead zinc district

  11. Sedimentary Ore Deposits • Concentration of ore minerals due to • Weathering (laterite, supergene) • Sorting due to gravity (placer) • Chemical precipitation (BIF, evaporite) • Laterite • Tropical weathering to a residuum of Fe2O3 & Al2O3 • Preserved in the geological record as bauxite • Placers • Dense, heavy minerals become concentrated in stream bottoms • California gold deposits • Banded Iron formation • Formed in a O2 poor, early earth atmosphere, >2 billion years old • Fe as hematite

  12. In 2000, the estimated value of non-fuel mineral production for Michigan was $1.67 billion The state rose to sixth in rank among the 50 states in total non-fuel mineral production value Michigan accounted for more than 4% of the U.S. total Mineral Resources

  13. Portland cement Cement = binding agent in concrete Made from limestone, clay minerals and gypsum Michigan’s leading non-fuel mineral commodity Construction sand and gravel Crushed stone Magnesium compounds Salt Limestone Mineral Resources of Michigan

  14. Iron ore Largely extracted from BIF Michigan was the nation’s second leading iron ore-producing state in 2000 Copper Native Cu of hydrothermal origin Hosted in Precambrian basalt lava flows Last mine, the White Pine Mine, closed in 1997 Mineral Resources of Michigan