Mineral Resources

• Backbone of modern societies• Availability of mineral resources as a measure of

the wealth of a society• Important in people’s daily life as well as in

overall economy• Processed materials from minerals account for 5%

of the U.S. GDP• Mineral resources are nonrenewable

Mineral Resources

Mineral Value• Direct value

– Raw, recycles– Import, export

• Indirect value– Processes

• Value added– E.g., agriculture

Common Use of Mineral Products

METALLICHYDROCARBONNON-METALLIC

Mineral Resources and Reserves

• Mineral resources: Usable economic commodity extracted from naturally formed material (elements, compounds, minerals, or rocks)

• Reserve: Portion of a resource that is identified and currently available to be extracted legally and profitably

• Defining factors: Geologic, technological, economic, and legal factors

Reserves vs. Resources

• Reserves– Natural resources that

have been discovereddiscovered && can be exploited exploited profitablyprofitably with existing technology

– Oil – 700 billion barrels

• Resources– Deposits that we know

or believe to exist, but that are not exploitable today because of technological, economical, or political reasons

– Oil – 2 trillion barrels

Mineral Resources Problems• Nonrenewable resources

– Finite amount of mineral resources and growing demands for the resources

• Supply shortage due to global industrialization– More developed countries consuming disproportionate share of

mineral resources

• Erratic distribution of the resources and uneven consumption of the resources. – Highly developed countries use most of the resources; supply

varies

Major Import Sources (Table 14.2)

• Friends– Canada: Metals– United Kingdom: platinum, rare earths

• Other– China: graphite, tin, tungsten…– South Africa : platinum, fluorspar– Chile: arsenic, iodine

Responses to Limited Availability

• Find more sources

• Find a substitute

• Recycle

• Use less and make more efficient use of what is available

• Do without

Figure 14.3

Responses to Limited Availability

Geology of Mineral Resources

• Metallic ore: Useful metallic minerals that can be mined for a profit

• Technology, economics, and politics

• Concentration factor: Concentration necessary for profitable mining– Variable with types of metals– Variable over time

Genesis of Mineral Resources

Some Important Minerals and there Uses• Galena [PbS] – source of lead – car batteries

• Magnetite, Hematite [FexOy] – iron ore

• Bauxite [Al2O3*2H2O] – aluminum ore

• Chalcopyrite [CuFeS2] – copper ore

• Quartz [SiO2] – glass and electronic components

• Gypsum [CaSO4*2H2O] – sheetrock, plater of paris

• Sphalerite [ZnS] – zinc ore

• Calcite [CaCO3] – portland cement, soil conditioner, antacids

• Garnet [Al2(SiO4)3+other metals] – abrasives

• Olivine [(Fe,Mg)2SiO4] – silicon chips for computers

• Sulfur [S] – insecticides, rubber tires, paints, papermaking, etc.

• Halite [NaCl] – Table salt• Graphite [C] – lubricant, pencil lead• Feldspars [K,Ca,Na,Al, silicates] – porcelain, source of K• Any other element that is not a major component of a mineral• Gold [Au], Silver [Ag], Platinum [Pt], Titanium [ Ti], Tin [Sn], etc.

Plate Tectonics and Mineral Resources

• Plate boundaries are related to the origins of many ore deposits

• Plate tectonic processes (high temperature, high pressure, and partial melting) promote release and enrichment of metals along plate boundaries

• Common metal ores along plate boundaries are Fe, Au, Cu, and Hg, etc.

Daily Questions

• Within your groups, identify one task you all have completed today. Collectively think about the task and brainstorm. Produce a list of all of the mineral resources that were used in that task.

• Elements comprise > 0.1% (by weight) of the crust

• Form as principal component in minerals within common rocks – i.e. iron (Fe) Fe2O3

• Form very large deposits

• Form rock deposits

Geochemically Abundant Elements (GAE)

Geochemically Scarce Elements (GSE)

• Elements that comprise < 0.1% (by weight) of the crust

• Do not form as principal component in minerals within common rocks, usually occur as a substitute in rock forming minerals

• Form small deposits• Ore minerals include sulfides, native elements,

etc.

Mineral Deposits

• Elements need to be concentrated• Minimum Grade - minimum amount of element

necessary to economically mine element• Minimum Concentration Factor (MCF) –

Minimum Grade divided by the Crustal Abundance – GAE have MCF < 100

– GSE have MCF > 100

Comparison of Concentrations of Elements in the Earth’s Crust with Concentrations needed to operate

a Commercial Mine

Element Natural Concentration in Crust (% by Weight)

Concentration Required to Operate a commercial mine (% by Weight)

Enrichment Factor

Aluminum 8 24-32 3-4

Iron 5.8 40 6-7

Copper 0.0058 0.46-0.58 80-100

Nickel 0.0072 1.08 150

Zinc 0.0082 2.46 300

Uranium 0.00016 0.19 1200

Lead 0.00010 0.2 2000

Gold 0.0000002 0.0008 4000

Mercury 0.000002 0.2 100,000

Process that concentrate elements

• Igneous Processes– Hydrothermal– Magmatic

• Sedimentary Processes– Mechanical– Chemical

• Metamorphism Processes• Groundwater Processes

• Precipitation of metallic ions from hot, ion-rich fluid

• Fluid could be– Magmatic– Groundwater– Oceanic water

• Magmas heat up the water• Water flows into fractures,

faults, joints, etc. where it cools and precipitates (deposits) the metals

Hydrothermal Processes

Magmatic Processes• Gravity Settling

– Dense, early-crystallizing minerals sink to the bottom of the magma chamber

• Filter Pressing– Tectonic force compress a

magma chamber and force the still-liquid portion into fractures, creating large crystals

• These processes have produced large bodies of iron, chromium, titanium, and nickel

Sedimentary Processes• Clastic

– Weathering of rock also weathers out elements of interest

– Generally, the elements are heavy and are deposited when a streams competence is low.

– Placer deposits, i.e. gold

Placer Gold

Sedimentary Processes• Chemical

Precipitates– Water with high

concentrations of elements is evaporated

– Evaporation of water leaves the elements

– Ex. Salts, Iron, etc.

Metamorphism

• Alteration of rock concentrates the elements

• The heat and pressure force out the GSE (“impurities”)

• Chemical weathering removes soluble material.

• Ore material (elements of interest) are left behind in a concentrated residue.

Weathering

Groundwater• Secondary enrichment• Groundwater dissolves and carries elements in

solution• Chemical conditions change and the elements are

precipitated (deposited) out.• Ex. Lead

Groundwater• Secondary enrichment• Groundwater dissolves and carries

insignificant elements in solution• Insoluble elements of interest remain.• Ex. Aluminum

Ore Mineral

• Ability to separate and readily process the metal (element) from the ore material.

• Need to look at– The energy to process the material– The cost to process the material– The value of the metal

• Basically, is it profitable to mine the metal?

Mineralogical Barrier

• Increase in energy and cost associated with the production of GSE

Energy and Costper mass of

metal

$

Grade of metal (element) in rock HighLow

GAEGSE

Mineralogical Barrier

FixedCosts

Metals trapped in minerals (silicates)

Metals the have been concentrated

Ways to overcome the mineralogical barrier

• Improve technology

• Recycle

• Come up with cheap energy to break silicate bonds

Daily Assignment

Place the following on the Venn Diagram

1.Gold

2.Oil

3.Coal

4.Iron

5.Copper

6.Gravel

15

2, 3, 6

4

Plate Tectonics and Resources