Economic Geology: Mineral Uses

Economic Geology Overview

• Economic geology deals with the Earth's materials that can be used for economic and industrial purposes.

Mineral Uses

• Silver (Ag) is used in photosensitive applications.
• Aluminum (Al) is used in construction and to make wire.
• Arsenic (As) is used as a hardener in batteries and as a preservative.
• Barium (Ba) is used in heavy cement and drilling mud.
• Boron (B) is used to make borosilicate glass.
• Beryllium (Be) has high melting point applications.
• Bismuth (Bi) as a nontoxic replacement for lead (Pb).
• Cadmium (Cd) is used in batteries and for plating as well as to stabilize plastics.
• Cobalt (Co) is used in superalloys for turbine engines.
• Chromium (Cr) is used to make corrosion-resistant steel.
• Cesium (Cs) is used in electronics due to being highly electropositive.
• Copper (Cu) is used to make wire.
• Carbon (C) is used to make diamonds used in jewelry, abrasives, and cutting tools.
• Fluorine (F) is used in the chemical industry to produce hydrofluoric acid.
• Gallium (Ga) is used in lasers and light-emitting diodes.
• Germanium (Ge) is used in semiconductors, transistors, and optics.
• Mercury (Hg) is used in electrical switches.
• Hafnium (Hf) is used in nuclear control rods.
• Indium (In) is used for thin films in LCDs.
• Potassium (K) is used as whitener, ceramic flux, and fertilizer.
• Manganese (Mn) is used to make steel.
• Molybdenum (Mo) is used for hardening high-stress steel.
• Niobium (Nb) is used in superalloys that are heat-resistant.
• Nickel (Ni) is used to make stainless steel.
• Lead (Pb) is used in batteries and ceramics.
• Platinum (Pt) is used in catalytic converters.
• Rhenium (Re) is used as a catalyst for producing lead-free fuel.
• Rare earth elements (RE) are used in electro-optical devices.
• Sulfur (S) is used to make sulfuric acid and in cosmetics.
• Antimony (Sb) is a flame retardant and a hardener in batteries.
• Selenium (Se) is used as a photoconductor in photocopiers.
• Strontium (Sr) is used to make glass for TV tubes.
• Tantalum (Ta) is used in capacitors found in cell phones.
• Tellurium (Te) is used in semiconductors and solar cells.
• Thorium (Th) is used to make high-temperature ceramics.
• Thallium (Tl) is used in radiation detection and infrared sensors.
• Titanium (Ti) is used as a white pigment in paper and paint.
• Uranium (U) is used as nuclear fuel.
• Vanadium (V) is used as an alloy with aluminum.
• Tungsten (W) is used as a catalyst and metal hardener.
• Zinc (Zn) is used for galvanized steel and rubber production.
• Zirconium (Zr) is used as a refractory in ceramics.
• Approximate price per ounce for some metals:
  • Gold costs approximately $2,000.
  • Platinum costs approximately $1,100.
  • Palladium costs approximately $3,100.
  • Rhodium costs approximately $21,000.

Mining & Consumption Rates

• Average North Americans use about 20,000 kg per year of mined commodities.
• The world's average consumption rate is approximately 9,000 kg per person annually.
• Around 54 billion tonnes of mined materials are extracted from the Earth each year.
• Useful metals in Earth's crust are geochemically scarce which are typically present at concentrations <0.1 wt%.
• Scarce metals usually occur as atomic substitutions within abundant rock-forming minerals.
• Metals like Ni, Co, and Cu substitute for common elements such as Mg and Ca in rock-forming minerals.
• Meeting the goals of the Paris Agreement for climate stabilization may require a 4x mineral requirements for clean energy technologies by 2040.
• Hitting net-zero emissions globally by 2050 requires 6x times mineral inputs in 2040.
• Zero-emission future by 2035 requires at least 74 lithium mines, 62 cobalt mines, 72 nickel mines, 97 natural graphite mines and 54 synthetic graphite plants.
• Lithium is primarily supplied by Australia as China dominates lithium refining with 75% of supply.
• Over 50% of lithium and copper production occurs in high water-stress areas.

Human History & Mineral Use

• Evidence indicates mining of flint, chert, and obsidian for tools occurring over 160,000 years ago.
• Metals were first used >20,000 years ago.
• Native copper (Cu) and gold (Au) were among the first metals utilized.
• Approximately 6,000 years ago, copper extraction began through smelting sulfide ores.
• About 5,000 years ago lead (Pb), tin (Sn), zinc (Zn), and silver (Ag) smelting started.
• Around 4,000 years ago the mixing of metals to create alloys was developed, bronze is copper and tin.
• Approximately 3,000 years ago iron (Fe) ore smelting was introduced and coal replaced wood use in China.
• Agricolla's De Re Metallica (1556) to Lindgren's Mineral Deposits (1913) marks 350 years of knowledge on ore deposits.

Ore Minerals

• Scarce metals' ore minerals are mostly found as sulfides (e.g., FeS2, ZnS, PbS, CuFeS2).
• Oxides are less common but include ore minerals for tin (Sn) and tungsten (W).
• Gangue is the term for unwanted/non-valuable minerals in ore deposits.
• Acid mine drainage is caused by the oxidation of pyrite (FeS2), which creates iron hydroxide and sulfuric acid.

Creation of Ore Deposits

• Ore deposits are created via:
  • Source rocks or magma enriches in metals.
  • Fluid (melt) transports the metals from source.
  • Physical or chemical trap concentrates metals into an ore deposit.
• Examples of Source, transport and trap settings are:
  • Layered mafic intrusions, fractional crystallization, and sulfide settling.
  • Volcanic eruptions, geothermal fluids, and hydrothermal precipitation.
  • Erosion of a source, fluvial transport, and gravity concentration.

Mineral Deposit Origins

• Hot aqueous solutions flow through fractures and pores, which lead to hydrothermal mineral deposits.
• Magmatic mineral deposits form through magmatic processes in igneous rocks.
• Sedimentary mineral deposits are formed from precipitation from modified seawater.
• Placer deposits are formed from flowing surface water concentrates heavy minerals.
• Residual and supergene mineral deposits form from weathering processes.
• Mineral deposits are found in a variety of plate tectonic settings.

Metallic Mineral Deposits

• Magmatic ore deposits occur, in different magma types the metals concentrate during cooling and crystallization.
• Metals like copper and gold found in felsic magmas and nickel in mafic magmas.

Magmatic Deposits

• Fractional crystallization / magmatic differentiation of heavy minerals concentrate heavy minerals.
• Chromite, a high-density mineral, sinks to bottom of magma chamber.
• Immiscibility segregates metal-rich (sulfide) liquid from crystallizing magma, metal-sulfide melts settle.
• Pegmatites result from melt rich in volatiles/rare elements in late crystallization with large crystals.

Deposits & Metamorphism

• Skarns form through country rock metamorphism via intrusion and reactive carbonate-rich rocks act as a chemical trap.
• The main metals found in skarns include: sphalerite (zinc), chalcopyrite (copper), and scheelite (tungsten).

Hydrothermal Ore Deposits

• *Veins result with igneous Activity:
  • Best known and important in hot wate, expelled from intrusions.
  • The metallic ions create deposits.
  • Open fractures in hydrothermal fluids creates vein minerals while they cool.
• Common vein minerals are quartz and calcite.

Origin of Hydrothermal Fluids

• Dissolved water is released when magma crystallizes.
• Rainwater circulates into the crust near hot intrusions.
• Hot seawater is circulated into the ocean crust near mid ocean ridges.
• Metal-rich fluids result from metals that leached out of rocks.
• As fluids rise and cool it precipitates metals.

Hydrothermal ore deposits cont.

• Disseminated veins result from igneous activity:
  • Metals distributed from disseminated deposits throughout rock rather than concentrated in veins
• Porphyry copper deposits are from hydrothermal veins and disseminations in large porphyritic intrusions.
• VMS deposits are formed by Volcanogenic Massive Sulfides that lenses of sulfide minerals.

Creating VMS deposits

• Cold seawater influx.
• Alteration of ocean crust over a low temperature.
• Low pH due to high acidity.
• Seawater is heated.
• Copper, zinc, iron, gold, and sulfur are leached from surrounding rock.
• Hydrothermal precipitates are created after coming into contact with cold seawater.
• VMS deposits which occur in seafloor lavas can be as old as 3 Ga.
• Lenses of copper,iron, zinc and lead sulfides accumulate on the seafloor and get burried.
• Sedimentary exhalative deposits (SEDEX) occur in sedimentary basins as massive sulfide deposits from seafloor hydrothermal vents ex: Red Sea's Atlantis II Deep.
• Thin layers of metallic sulphides are formed.

Origins

• Oxidized Uranium that contain brines flow into sedimentary rock which forces reduced uranium minerals upward.
• Sediments can create Mississippi Valley-type Deposits, oxidized metal-bearing brines migrates toward the basin.
• Calcite, dolostone, and sandstone minerals occur in limestone environments.

Sedimentary Ore Deposits

• Reducing conditions in Earth's history caused dissolves Iron to accumulate in basins.
• From this photosynthesis caused to generate oxygen and precipitate iron minerals

Sedimentary Hosted Deposits

• Placer deposits are formed when currents deposit heavy metals .
• ex: gold, platinum, diamonds, tin concentrate in rivers.
• South Africa has placer deposits of gold (paleoplacer deposits) with the most gold on Earth(Witwatersrand Basin).
• Conglomerates get deposited.

Weathering Origin

• Residual enrichment is when weathering concentrates metals into valuable concentrations.
• Laterite, (enriched in Fe, Al, Ni) results when parent rocks leach out elements.
• Laterite can only occur in rainy climates and not glaciated regions as bauxite created in last 25 Myr.
• Supergene forms when soluble minerals near the table dissolves surface mineral which is depth reprecipitated and located in arid climates.

Nonmetallic Resources

• Nonmetallic mineral resources are used for various different Geological Occurrences.

Significant Industrial Mineral Deposits in Canada

Diamonds (Carbon)

• Most diamonds are found in rare ultramafic igneous rocks(kimberlites) with over 160 km in depth but is exposed on the surface.

Fossil Fuels - Coal (Carbon)

• Decay and compression that's high in resins, waxes, and lignins.
• • Warm, moist, calm, low oxidation in swamps (anoxic environment).
• Peat turns to lignite, lignite turns to bituminous then to anthracite.

World Reservoirs of Fossil Fuels

• Most reservoirs are in Canada as well as Saudi Arabia.

Oil & Gas (Carbon)

• Derived from marine plants/animals, complex process with burial over millions of years produces hydrocarbon.

Oil Trap Styles

• Petroleum formed into shales and migrated upward.
• Reservoirs must be porous and permeable and needs a trap(folds, faults or impermeable seals).

Tar & Oil Sands

• Alberta has major resources with 20 %mined and remainder is needed to be heated with over 2trillion barrels.

Fossil Fuels Shale

• Kerogen is used as a wax which becomes fuel.
• There is a high exploitation energy.

Shale gas benefits and negatives

• Negatives include contamination which is environmental.
• Positives would be the cost.

Fossil fuels gas hydrates

• Structures come from water molecules.
• From the breakdown of material to product methane.

Impacts of gas hydrates

• May increase temp and atmosphere.