Lecture 29: Mineral Resources Flashcards
-Introduction to Mineral Resources -Types of Mineral Deposits -Environmental Impacts of Mining
What are geochemically abundant elements?
Those that comprise more than 0.1% of the crust.
What are geochemically scarce elements?
Those that comprise less than 0.1% of the crust.
What are metallic minerals?
Those we mine for their constituent metals.
What are nonmetallic minerals?
Those that we mine for their chemical or physical properties.
What is a resource?
It is a naturally occurring accumulation of material in concentrations and amounts that make extraction currently or potentially feasible.
What are reserves?
They are resources that can be exploited economically under present conditions.
What are mineral deposits?
They are localized concentrations of a resource.
What are ore deposits?
They are a mineral deposit that can exploited economically.
What are the five parts of the rock cycle that mineral deposits can be derived from?
1) Magmatic concentration of elements
2) Hydrothermal concentration of elements
3) Weathering and concentration of the resulting residual material in place
4) Physical sediment concentration by moving water
5) Chemical sedimentary concentration
What is fractional crystallization?
When a magma chamber cools, minerals being to crystallize as a function of temperature.
What is crystal settling
The mineral crystals sinks to the bottom of the chamber because they are denser than than surrounding magma.
What is crystal flotation?
The mineral crystals float above the magma because they are less dense than the surrounding magma.
What is filter pressing?
When remaining magma moves through a fracture, leaving precipitated crystals behind.
How does Pegmatites form?
They form as granitic, water-rich magma slowly cools.
-Some minerals that form do not fit into the minerals crystal lattices which causes the coarse-grained mineral.
What are Kimberlites?
They are fragmental volcanic rocks from particularly explosive eruptions.
-The magma comes from the mantle beneath old, stable continental lithosphere and it contains a variety of high-pressure minerals including diamonds.
What are two ways that a hydrothermal mineral deposit may form?
1) Heated water emerges directly from a magma chamber through veins and fractures.
2) Circulating groundwater is heated in volcanic areas. This hot groundwater alters minerals, and dissolves trace amounts of metals. As the water moves away from the magma, three things can happen.
-it may cool rapidly
-it may boil
-it may interact with oxygen
These processes may reduce the solubility of dissolved metals, which precipitate as minerals.
What are vein hydrothermal deposits?
Fractures that have filled with mineral deposits
What are hydrothermal stratiform deposits?
Deposits that form when hydrothermal water escapes to the seafloor and deposits a layer of mineral particle, resulting in volcanogenic massive sulfide (VMS) deposits near current and former tectonic boundaries.
What are hydrothermal disseminated ore deposits?
Deposits that form when hydrothermal water soaks through porous rocks and deposits minerals particles in pore spaces.
How are residual deposits created?
When chemical weathering dissolves some components of rock, leaving behind more resistant material
- useful minerals may be concentrated.
How do laterites form?
When rocks are weathered in tropical regions that have a high and variable annual precipitation, oxidizing pore water, and good drainage, high leaching rates can occur, which can result in laterites.
What are lateritic ores?
Ones that are rich in metals such as nickel, aluminum, and iron.
How are placer deposits formed?
The area where flowing water is effective at sorting sedimentary particles by size and density and dense minerals concentrate in sands.
What are some minerals that concentrate in placer deposits?
- Gold
- Platinum
- Zircons
- Titanium (rutile)
- Diamonds
- Tin (cassiterite)
What is aggregate?
Supplies of sand, gravel, and clay that are used for construction in urban areas.
What are two ways aggregate deposits can be made?
- Naturally (moving glacier leaves behind finely ground rock)
- Mined larger rocks are ground down to the necessary size.
How is cement formed?
When limestone is heated with clay, other silicates, and/or sulfates.
What are evaporites?
They are chemical sedimentary rocks formed by the evaporation of seawater and the subsequent precipitation of minerals from solution.
What are some important evaporites?
- gypsum
- halite
- potash
What is the major source of iron?
Banded Iron Formations
Where do banded iron formations occur?
In sedimentary rocks 2 Ga and older.
What are some physical consequences of mining?
- Increased erosion because of the removal of plants
- Sediment and contaminants are added to streams
- Acid mine drainage can become a threat to surrounding groundwater and surface water resources, aquatic ecosystems, and human health
What are mine tailings?
The byproducts that remain after resources are extracted from a deposit.
What is a consequence of mine tailings?
They may be reactive when exposed to oxygen and water and could cause surrounding surface and groundwater ph to fall to acidic levels.
What is smelting?
It is a process used to extract the target metal from a source ore.
-The metal itself has to be separated from compounds
What is a consequence of smelting?
The compounds released cause an increase in greenhouse gases that may lead to the formation of acid rain.
What is the issue with the way humans dispose of manufactured products?
They end up in landfills, taking the resource out of circulation and opening up the possibility of leaching of metals into water resources.
