Land Resources

Earth’s Crust: The Earth’s crust is composed of minerals and rocks. Minerals are made of elements or inorganic compounds that are solid. Rocks are a combo of one or more minerals. The Earth’s crust is made of igneous, sedimentary, and metamorphic rock.

Rock Cycle: Igneous rock is formed below or on the earth’s surface when molten rock wells up and hardens. They form the bulk of the earth’s crust. Examples: Granite, Basalt, Pumice. Sedimentary rock is formed from small, eroded pieces of rock that are carried to downhill sites. Layers accumulate over time and an increase of weight and pressure plus dissolved minerals bind the sediment particles together to form sedimentary rock. Examples: Rock salt, Iron ore, Flint. Metamorphic rock is produced from preexisting rock that is subjected to high temperatures, high pressures, chemically active fluids, or some combination of these. Examples: Quartz, Slate, Marble.

Rock Cycle Continued… The rock cycle is the interaction of physical and chemical processes that change rock from one type to another. It is the slowest of the earth’s cyclic processes. KNOW THIS ROCK CYCLE 

What does NONRENEWABLE mean? Minerals: Mineral resources are nonrenewable materials that we can extract form the earth’s crust. What does NONRENEWABLE mean? We can find and extract over 100 minerals from the earth such as metallic mineral resources, nonmetallic mineral resources, and energy resources.

ORE: Ore is rock containing one or more metallic minerals to be mined profitably. The U.S. Geological Survey divides nonrenewable mineral resources into four major categories: Identified Resource Reserves Undiscovered Reserves Other Resources

1. Identified resources with a known location, quantity, and quality, 2. Reserves, which are identified resources that can be extracted profitably at current prices, 3. Undiscovered reserves, which are potential supplies of a mineral resource assumed to exist, and 4.Other resources, which are undiscovered resources and identified resources not classified as reserves.

Nonrenewable Mineral Resources Several methods are used to detect minerals Aerial photos & satellite images - outcrops Radiation-measuring equipment – detect deposits Magnetometer – record changes in the Earth’s magnetic field Gravimeter – measures differences in gravity due to density differences in various ore deposits Underground methods – deep well drilling & core samples Seismic surveys – analyzing shock waves by detonation Chemical analysis – leaching into water & plants

Mining Surface mining – equipment strips away the surrounding and unwanted material called the overburden (as waste it is called “spoil”) Open-pit mining – equipment digs a hole & extracts ore Dredging – draglines scrape up underwater minerals Area strip mining – terrain flattened prior to digging Contour mining – cuts terraces into the terrain Mountain-top removal – explosives & powerful shovels expose ore Sub-surface mining – deep vertical shafts, explosives, heavy equipment used for extraction

Pros & Cons of Surface & Subsurface Mining Surface mining is cheaper than subsurface mining. (Subsurface is expensive) Surface mining is safer than subsurface mining. (Subsurface was dangerous) Subsurface mining disturbs the environmental less than surface mining. (surface destroys more) Subsurface reclamation efforts are cheaper and easier than surface mining. *Reclamation = Recovering/fixing the degraded environment.

Environmental Impacts Scarring & disruption of terrain Collapse of land above mines Toxin laced mining waste & air pollution Acid mine drainage Overall effects on the health of humans and wildlife can be devastating

Mining Supply Economic depletion – cost is more to find and process than its worth on the open market Recycle or reuse Waste less Use less Find a substitute Do without Depletion time = depletion /time “Should we continue to mine?”

Mining Lower Grade Materials Achieved with current technologies Can be limited by Increase cost of mining large quantities of ore Availability of fresh water Environmental impact of increased waste & pollution Environmental impact of disrupting the ecosystem surrounding the mine

Microbes in Mining Bio-mining or in-situ mining is done by inoculating an ore vein with microbes that act on a specific ore Microbe loosens the ore and provides a means to extract it by flooding the mine Flood water is filtered for the desired ore and recycled back to the mine Ex. Copper ore is digested by thiobaccillus ferroxidans Bio-mining is a slow process