Mining and Natural Resources

• The Latrobe Gold Nugget, displayed in the London Natural History Museum, weighs 717 grams and exhibits a rare cubic form.
• Most gold nuggets grow in confined spaces, which prevents the observation of the mineral's euhedral nature.
• Geologic knowledge is key for locating materials of economic value.
• Fertilizer ingredients include nitrogen from the atmosphere, potassium from the hydrosphere, and phosphorus mined from the lithosphere.
• Without mining and processing natural materials, modern civilization would not exist.

Mining

• Defined as extracting valuable materials from the Earth for societal use, including solids like gold, iron, coal, diamonds, and fluids like oil and natural gas.
• The oldest mine, dating back 40,000 years, is the Lion Cavern in Swaziland, noted for hematite (iron ore) extraction, for use as red dye.

Renewable vs. Nonrenewable Resources

• Renewable resources can be reused or replenished in a short human life span.
• Nonrenewable resources may be exhausted and in short supply.
• Mining extracts nonrenewable resources that cannot be replaced on a human time scale.
• Solar energy comes from fusion in the Sun.
• Wind energy is related to solar energy and can be used to sail ships and power windmills.
• Geothermal energy is sourced from the Earth's heat.
• Hydroelectric dams generate energy by using falling water to activate turbines.
• Ocean tides are a reliable energy source.
• Nonrenewable resources include gold, lead, copper, diamonds, natural gas, oil, and coal.
• Coal use has decreased due to the lower cost and environmental impact of oil and natural gas.

Ore

• Refers to a body of material from which valuable substances can be mined at a profit.
• Ore mineral resource is potentially extractable ore, while ore mineral reserve refers to a proven, profitable amount of extractable ore.

Mining Techniques

• Mining style is determined by technology, social license, and economics.
• Fluid resources like oil and gas are extracted by drilling wells and pumping.
• Solid resources are extracted using surface or underground mining.
• Environmental impacts are usually greater from surface mining.
• Surface mining is used to remove material from the Earth's outermost part.
• Open pit mining is used for shallow, broadly disseminated resources.
• Strip and mountaintop mining are surface techniques used for layered resources like coal.
• Underground mining is used for higher-grade, localized, or concentrated resources.
• Chemical agents can be used in underground mining to dissolve the target mineral.

Concentrating and Refining

• Ore minerals occur mixed with less desirable components called gangue.
• Concentrating is the process of physically separating gangue minerals from ore-bearing minerals.
• Smelting is separating a desired element from a host mineral by chemical means, including heating.
• Refining involves removing trace metals, such as gold or silver, from a metal like copper.
• Refining methods include mechanical separation, heating, or smelting.

Fossil Fuels

• Are extractable sources of stored energy from ancient ecosystems, including coal, oil, petroleum, and natural gas.
• Fossil fuels are formed by photosynthesis.
• Burning fossil fuels produces carbon.
• Fossil fuels contain hydrocarbon compounds produced in ancient Earth surface environments, and environments rich with organic matter tend to accumulate fossil fuels.

Oil and Gas

• Petroleum is derived from organic-rich shallow marine sedimentary deposits.
• Oil is the liquid component of petroleum, while natural gas (mostly methane) is the gas component.
• As sediments lithify, increasing pressure and temperature cause oil and gas to migrate from a source rock to a reservoir rock.
• Traps are subsurface features that halt petroleum migration.
• Sequence stratigraphy is used to study sedimentary facies variations caused by sea level changes, which is important for predicting locations of source and reservoir rocks.
• A petroleum play refers to geologically related oil fields or prospects in a particular area.

Tar Sands

• Tar sands are sandstones containing highly viscous hydrocarbons (bitumen) that cannot be readily pumped.
• Bitumen can be extracted by heating or mixing with solvents.
• Tar sand reserves are largest in Alberta, Canada.

Oil Shale

• Oil shale contains tight oil locked in a non-permeable reservoir.
• Extracting oil from shale requires mining and heating the material.

Fracking

• Hydraulic fracking is used to extract oil and gas from shale and other tight resources.
• It involves injecting high-pressure water, sand, and chemicals underground to create fractures in rocks.
• Fracking can lead to groundwater contamination and seismic activity.

Coal

• Coal resources come from fossilized swamps, and older deposits may come from algal buildups.
• Coal consists of carbon, hydrogen, nitrogen, sulfur, oxygen, and minor amounts of other elements.
• Increased heat and pressure concentrate the carbon in coal.
• The sequence of coal evolution is swamp debris -> peat -> lignite -> sub-bituminous coal -> bituminous coal -> anthracite -> graphite.
• Anthracite is the highest metamorphic grade coal and provides the highest energy output.
• Carbon fiber is a potential application for coal.

Mineral Resources

• Divided into metallic and nonmetallic resources, both of which are nonrenewable.
• Metallic resources are valued for their metal content.
• Non-metallic resources include construction materials, salt deposits, fertilizer components, and gemstones.

Types of Metallic Mineral Deposits

Magmatic Processes

• Layered intrusions can host ore minerals of copper, nickel, platinum, palladium, rhodium, and chromium.
• The Stillwater Complex in Montana is a major source of platinum and palladium.
• The largest magmatic deposits are chromite deposits in the Bushveld Igneous Complex in South Africa.
• Pegmatites form from volatile-rich magma fluids and contain large crystals of rare elements like beryllium, lithium, tantalum, niobium, tin, and gold.
• Kimberlite pipes transport ultramafic magma and diamonds from Earth's mantle to the surface.

Hydrothermal Processes

• Black smokers at mid-ocean ridges create volcanogenic massive sulfide (VMS) deposits containing copper, zinc, lead, gold, and silver.
• Porphyry deposits are hydrothermal deposits containing low-grade ores of copper, molybdenum, and tin.
• Supergene enrichment is a weathering process that enhances the metal content of porphyry copper deposits, converting lower-copper minerals to higher-copper minerals.
• Skarn deposits form when magma-derived fluids react with carbonate rocks, creating calcium-magnesium-silicate minerals and high-grade ores containing iron, copper, zinc, and gold.
• Sediment-hosted disseminated gold deposits involve microscopic gold inclusions in pyrite crystals, formed by low-grade hydrothermal reactions.
• Carlin-type deposits are disseminated gold deposits found near Carlin, Nevada.

Non-magmatic Geochemical Processes

• Redox reactions occur due to changes in the amount of available oxygen and concentrate metals.
• Uranium deposits are an example of redox concentration, with uranium precipitating as uraninite under reducing conditions.
• Banded iron formations (BIFs) are interbedded layers of iron oxide, chert, and shale, formed by cycles of oxygenating iron-rich waters.
• Mississippi Valley-type deposits are lead and zinc deposits formed by hot fluids in limestone or sandstone.
• Sediment-hosted copper deposits are formed diagenetically by groundwater fluids in permeable rocks.

Surficial Physical Processes

• Weathering of soils and mineral deposits can form surficial deposits like bauxite, an aluminum ore.
• Hydraulic sorting concentrates high-density minerals into placer deposits, containing native gold, platinum, zircon, ilmenite, rutile, magnetite, diamonds, and gemstones.

Environmental Impacts of Metallic Mineral Mining

• Land disturbance, tailings piles, and increased erosion, which lead to acid rock drainage (ARD) that produces acidic streams and toxic metals.
• Waste rock contains pyrite, which reacts with oxygenated water to release metal ions and lower pH.

Nonmetallic Mineral Deposits

• Vital to ancient and modern society.
• The most basic industrial mineral is building stone like limestone, granite, slate, and marble.
• Limestone is processed into plaster, cement, and concrete.
• Aggregate is used in concrete, roads, and foundations.

Evaporites

• Deposits form in restricted basins where water evaporates faster than it recharges such as around the margins of the Great Salt Lake in Utah, and adjacent to the Dead Sea that borders Israel and Jordan.
• Evaporite minerals include halite (table salt), gypsum (used in drywall and fertilizer), sylvite (potassium chloride), and bischofite (magnesium chloride) which are used in agriculture, medicine, food processing, and other applications.

Phosphorus

• Essential element that occurs in the mineral apatite.
• Phosphorite rock, a marine sedimentary rock, is mined to make fertilizer.