Geology and Nonrenewable Minerals Chapter 14 PART 1

GEOLOGIC TIMESCALE Geologists have divided Earth's history into a series of time intervals. The geologic time scale was constructed to visually show the duration of each time unit. The Earth is 4.6 billion years old. The geologic processes have been happening for a very long time. Humans just showed up at the end.

GEOLOGIC TIMESCALE The time intervals are variable in length. This is because geologic time is divided using significant events in the history of the Earth. New biological developments Mass extinctions

14-1 What Are the Earth’s Major Geological Processes and Hazards? Concept 14-1A Gigantic plates in the earth’s crust move very slowly atop the planet’s mantle, and wind and water move the matter from place to place across the earth’s surface. Concept 14-1B Natural geological hazards such as earthquakes, tsunamis, volcanoes, and landslides can cause considerable damage.

The Earth Is a Dynamic Planet The earth’s interior consists of: Core: innermost zone with solid inner core and molten outer core that is extremely hot Mantle: liquid rock with a rigid outer part (asthenosphere) that is melted pliable rock Crust: layer of solid rock (lithosphere) which underlies the continents and the oceans Continental crust Oceanic crust

The Earth Beneath Your Feet is Moving Plate Tectonics The theory that Earth’s crust is divided into huge tectonic plates that float on magma or molten rock. Convection currents within the mantle move the plates around. Evidence: Puzzle-like fit of the continents Matching plant/animal fossils on opposite sides of oceans Matching rock layers on opposite sides of oceans Evidence of past climates

The Earth’s Major Tectonic Plates

Major Features of the Earth’s Crust and Upper Mantle

Tectonic Plate Boundaries Plates move apart at divergent plate boundaries. Mid-ocean ridge – the site of sea-floor spreading

Tectonic Plate Boundaries Plates grind into one another at convergent plate boundaries. Folded mountains Volcanic mountains

Tectonic Plate Boundaries Plates slide past one another at transform plate boundaries.

Some Parts of the Earth’s Surface Build Up and Some Wear Down Internal geologic processes Generally build up the earth’s surface Result from the heat generated by the Earth’s interior External geologic processes Wear down the Earth’s surface and move it around Result from solar energy and gravity (wind, flowing water) Weathering – Processes that break rocks down into smaller pieces Plays key role in soil formation Different kinds of rock will result in different soil properties

Volcanoes Release Molten Rock from the Earth’s Interior Volcanoes are simply vents in the earth's surface through which lava and other volcanic products erupt.

Earthquakes Are Geological Rock-and-Roll Events The sudden release of energy stored up by the movement of tectonic plates Energy travels as seismic waves, each with own type of movement and speed. P-wave S-wave Surface waves

14-2 How Are the Earth’s Rocks Recycled? Concept 14-2 The three major types of rocks found in the earth’s crust—sedimentary, igneous, and metamorphic—are recycled very slowly by the process of erosion, melting, and metamorphism.

There Are Three Major Types of Rocks A very slow geochemical cycle involves three types of rock found in the earth’s crust: Igneous rock (granite, pumice, basalt) Solidified lava or magma Sedimentary rock (sandstone, limestone, shale) Fusion of eroded sediments Metamorphic rock (slate, marble, quartzite) Application of heat / pressure

Natural Capital: The Rock Cycle Is the Slowest of the Earth’s Cyclic Processes

14-3 What Are Mineral Resources, and what are their Environmental Effects? Concept 14-3A Some naturally occurring materials in the earth’s crust can be extracted and made into useful products in processes that provide economic benefits and jobs. Concept 14-3B Extracting and using mineral resources can disturb the land, erode soils, produce large amounts of solid waste, and pollute the air, water, and soil.

We Use a Variety of Nonrenewable Mineral Resources Mineral – naturally occurring, inorganic, solid element or compound with a definite chemical composition and a regular internal crystal structure. Mineral resource (Ore) – a deposit of minerals that can be extracted and processed into useful materials at an affordable cost. Deposits of nonrenewable mineral resources in the earth’s crust vary in their abundance and distribution. High Grade Ore – high percentage of desired mineral Low Grade Ore – low percentage of desired mineral

We Use a Variety of Nonrenewable Mineral Resources Examples of nonrenewable metal and nonmetal mineral resources: Aluminum – beverage cans, motor vehicles, aircraft Steel (alloy of iron and other elements) – buildings Copper – electrical and communications wiring Platinum – electrical equipment, industrial catalyst Gold – electrical equipment, jewelry, medical implants Sand – glass, bricks, concrete Limestone, - road rock, concrete, cement Manganese, Cobalt, Chromium – light bulbs, computers, automobiles, aircraft, etc.

Concentration of Minerals in Earth’s Crust Aluminum ~8% Iron ~5.8% most Fe and Al is in silicate minerals (like sand) and is, therefore, not used as an ore Titanium 0.82% Nickel 0.0075% Zinc 0.0082% Copper 0.0058% Lead 0.0013% Uranium 0.00016% Silver 0.000008% Gold 0.0000004%

Classification of Nonrenewable Mineral Resources The U.S. Geological Survey classifies mineral resources into four major categories: Identified: location, quantity, and quality or existence known based on direct evidence and measurements. Undiscovered: potential supplies that are assumed to exist. Reserves: identified resources that can be extracted profitably. Other: undiscovered or identified resources not classified as reserves

The Life Cycle of a Metal Resource The extraction, processing, and use of mineral resources has a large environmental impact. Mining of low grade ore requires more energy, water, and produces more waste.

Extracting, Processing, Using Nonrenewable Mineral and Energy Resources

Geology and Nonrenewable Minerals Chapter 14 PART 2

There Are Several Ways to Remove Mineral Deposits Minerals are removed through methods that vary widely in their costs, safety factors, and levels of environmental harm. The method used is based on mineral depth Surface mining: shallow deposits are removed Open pit mining Strip mining Subsurface mining: deep deposits are removed Underground shafts and/or tunnels

There Are Several Ways to Remove Mineral Deposits…Surface Mining Open Pit Mining Machines dig holes and remove ores, coal, sand, gravel, and stone. Toxic groundwater can accumulate at the bottom. World’s deepest diamond mine - Mirny, Siberia

There Are Several Ways to Remove Mineral Deposits…Surface Mining Strip Mining: Area Strip Mining Earth movers strips away overburden in order to remove the mineral deposit. Often leaves highly erodible hills of rubble called spoil banks. When the ore is dredged from rivers or streams, the unused piles are called tailings.

There Are Several Ways to Remove Mineral Deposits…Surface Mining Strip Mining: Contour strip mining When mining hilly or mountainous terrain Terraces are created As workers move up the slope, the spoils are dumped on the terrace below

There Are Several Ways to Remove Mineral Deposits…Surface Mining Sometimes whole mountain tops are stripped away to get to the ore below – Mountain-top removal This is a common practice for coal mining in Appalachian mountains

There Are Several Ways to Remove Mineral Deposits…Subsurface Mining Subsurface mining – shafts and tunnels are used to get to ore that is buried much deeper below the surface. A variety of configurations are used, depending on the situation.

There Are Several Ways to Remove Mineral Deposits Surface Mining Surface mining Cheap Safe for miners Large environmental destruction Subsurface mining Expensive Hazardous for miners Less environmental damage Subsurface Mining Mining Animation/Virtual Tour: http://www2.illinoisbiz.biz/coal/virtualtour/index.html

Mining Has Harmful Environmental Effects Scarring and disruption of the land surface Piles of mine spoils and tailings (99% of mined material is waste material) Subsidence Loss of rivers and streams Disruption of ground water flow patterns Acid Mine Drainage - sulfuric acid produced through weathering of iron sulfide in tailings 4FeS2 + 14H2O = 4Fe(OH)3 + 8H2SO4 Major pollution of water and air Contamination from heavy metals in mine tailings e.g. arsenic, mercury

Reclamation, or Ecological Restoration Reclamation – an attempt to return mined land back to its original state (or at least a functional ecosystem) Recreation Commercial use Active mining site Reclamation process has begun

Removing Metals from Ores Has Harmful Environmental Effects Ore extracted by mining has two parts: The Ore mineral which is the desired metal The Gangue (“gang”), or waste material Smelting – heating ore to release the metal Chemical solvents can be used as well Huge amounts of air and water pollution is produced Contaminated water or toxic sludge sits around in large pools or lagoons

14-4 How Long Will Supplies of Nonrenewable Mineral Resources Last? Concept 14-4A All nonrenewable mineral resources exist in finite amounts, and as we get closer to depleting any mineral resource, the environmental impacts of extracting it generally become more harmful. Concept 14-4B An increase in the price of a scarce mineral resource can lead to increased supplies and more efficient use of the mineral, but there are limits to this effect.

Mineral Resources Are Distributed Unevenly Most of the nonrenewable mineral resources are supplied by the United States, Canada, Russia, South Africa, and Australia The United States, Germany, and Russia (8% of the world’s population) consume about 75% of the world’s widely used metals. Strategic metal resources – minerals essential for a country’s economic and military strength Manganese, Cobalt, Chromium, and Platinum The U.S. has little or no reserves of these metals

Supplies of Nonrenewable Mineral Resources Can Be Economically Depleted Future supply depends on: Actual or potential supply of the mineral Rate at which it is used A rising price for a scarce mineral resource can increase supplies and encourage more efficient use. Aluminum Gold When it becomes economically depleted – costs more to extract/process a mineral than what its worth: Recycle or reuse existing supplies, waste less, use less, find a substitute, do without

Natural Capital Depletion: Depletion Curves for a Nonrenewable Resource Depletion time - The time it takes to use up a certain proportion (usually 80%) of the mineral reserves at a given rate of use Dashed vertical lines represent times when 80% depletion occurs.

Mining Legislation U.S. General Mining Law of 1872 Encouraged mineral exploration and mining of hard-rock minerals (gold, silver, copper, nickel) on U.S. public lands Developed to encourage settling the West (1800s) Until 1995, land could be bought for 1872 prices Estimated $285 billion of mineral resources now owned/ controlled by private companies, 1/5 are foreign. Surface Mining Control and Reclamation Act of 1977 Requires the reclamation of land surfaced mined for coal. There are no laws to control or reclaim lands from other types of mines, like hard-rock, etc.

14-5 How Can We Use Mineral Resources More Sustainability? Concept 14-5 We can try to find substitutes for scarce resources, reduce resource waste, and recycle and reuse minerals.

Solutions: Sustainable Use of Nonrenewable Minerals