Mineral Resources Flashcards

1
Q

What are earth resources?

A

All materials used by modern society are either derived directly or are manufactured from Earth:

  • Water
  • Wood
  • Food
  • Metals
  • Glass
  • Cement
  • Etc.
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2
Q

The availability and cost of mineral and rock products influence:

A

a country’s standard of living, economy, and position in the world.

Most people do not know where minerals occur naturally or how they are mined and processed

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3
Q

To survive, we need food, water, and shelter. Today, we also “need”:

A

phones, airplanes, cars, and computers

  • Use more resources per individual
  • Use a greater variety of resources from more sources
  • Synthesized new materials from raw resources
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4
Q

Basic need: food

A
  • Technology has allow food production to keep pace with growing population (irrigation, tractors, fossil fuels, fertilizers)
  • The more the population grows, the more land is diverted away from agriculture
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5
Q

Resources are either renewable or non-renewable

A

Renewable resources:

  • Replenished over short time scales (months or years)
  • Trees, light, water, animals, etc.

Non-renewable resources:

  • Exist on Earth in a fixed quantity
  • Replenished over thousands to millions of years
  • Minerals, soils, etc.
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6
Q

Mineral Resources

A

Natural concentrations that result from physical and chemical processes active in Earth’s crust

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7
Q

There are two main types of mineral resources:

A
  1. Metallic

2. Non-metallic

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8
Q

Which physical property of minerals does the term metallic describe?

A

Lustre

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9
Q

Non-Metallic Mineral Uses

A
  • Sulfur: matches, tires, bug spray
  • Halite: salt, rock salt
  • Diamond: rings, blades
  • Gypsum: cement, construction
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10
Q

Agricultural Minerals (fertilizer)

A
Nitrogen (N):
- For leaf growth
- Manufactured from the air
Phosphorus (P):
- Development of roots, flowers, seeds, fruit
- From phosphate-bearing minerals/bones
Potassium (K):
- Strong stem growth, movement of water in plants, promotion of flowering and fruiting
- From potash
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11
Q

Construction Minerals

A
  • Aggregates: crushed stone, sand (for cement), gravel
  • Clay: cement manufacture, industrial lubricant, beauty products
  • Gypsum: drywall, cement manufacture
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12
Q

Metal Mineral Uses

A
  • Tin: battery, brake pads, radiator, fuel tank, glass coatings, electronics, bearings
  • Gold: electronic connectors, switch contacts, fuel cells, heat protection linings
  • Tungsten: bearing linings, gear teeth coatings, integrated circuits, metallic films
  • Tantalum: parking sensors, HID headlamps, airbag systems, traction control, dashboard, electric mirrors, window mechanisms, in car entertainment
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13
Q

Metallic Minerals

A

Abundant if: excess of 0.1% by weight in average continental crust
- Al, Fe, Mg, Mn, Ti

Scarce metals: less than 0.1% by weight in average continental crust

  • often concentrated in sulfide deposits
  • Copper, lead, zinc, nickel, gold, platinum
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14
Q

Reserve

A

The portion of an identified resource that can be recovered economically.

An ore is a reserve of metallic minerals

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15
Q

7 Major Classes of Minerals

A
  1. Silicates (most abundant in crust)
  2. Native elements (scarce metals)
  3. Oxides
  4. Sulfides (scarce metals)
  5. Sulfates
  6. Halides
  7. Carbonates
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16
Q

How do mineral deposits form?

A

All Earth resources have been generated by one or more geologic processes
- The distribution of resources globally is caused mainly by plate tectonics because it controls: the position of the continents and the geologic process responsible for forming, modifying, and destroying earth resources

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17
Q

The processes that can form and concentrate mineral resources include:

A
  1. Subsurface processes (igenous + metamorphic processes)
  2. Surface processes (weathering, physical and chemical sedimentation)
  3. Shallow subsurface and diagenetic (conversion of sediment to sedimentary rock) processes
  4. Meteor impact and mantle melt
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18
Q

Some mineral deposits are widely distributed because

A

They form from a range of igneous, sedimentary, and metamorphic processes

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19
Q

Other mineral deposits are very localized because

A

There is only one process that allows them to form

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20
Q

Which igneous processes create mineral resources?

A
  • Continental bedrock: generally felsic/intermediate rocks (e.g granite)
  • Seafloor: mafic rocks (basalt/gabbro)
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21
Q

Igenous rocks can be used in their raw form as:

A

building materials (dimension stone) or as crushed stone. These are non-metallic resources.

22
Q

Basalts/gabbros form due to

A

partial melting in the subsurface (addition of volatiles/decompression)

23
Q

Granites form from:

A

partial melting in subsurface (addition of volatiles/decompression) and differentiation processes (partial melting, magma migration, crystal settling, magma mixing)

24
Q

Igneous rock formation details

A
  • Felsic magmas contain several % water; mafic magmas contain less
  • Quartz, K feldspar, plagioclase do not contain water
  • Micas and amphibole contain small amount of water
  • The rest of the water escapes along fractures and faults during and after emplacement
  • The hot water contains dissolved elements that do not get incorporated into felsic minerals (Cu, Pb, Zn, Ag, S)
  • Hydrothermal fluids move outwards from the magma and cool
  • Pressure drops, mineral precipitate in cracked = veins
  • Erosion may expose veins at the surface
25
Q

Disseminated deposits

A

Widely distributed small particles or veinlets associated with emplacement of magma above a subduction zone, so occur in a zone parallel to a subduction zone
- Subduction in the past produced the porphyry copper deposits in the US

26
Q

Disseminated deposit formation

A
  • The main body of magma rejects water and incompatible elements
  • Mineral-rich fluids migrate outward and crystallize in dikes, veins, and sills
  • Fluids enhance rate of crystallization; very large (>3cm) form
  • Rock has the same composition as granite, but with very large x-tals (pegmatite)
  • Can also contain minerals made of fluorine, berylluim, lithium, rare earth elements, and gemstones i.e tourmaline, emerald, and aquamarine
27
Q

Bowen’s reaction series:

A

Order of crystallization of mineral from a cooling melt

Discontinuous reaction (high T to low T): olivine, pyroxene, amphibole, biotite -> K feldspar, muscovite, quartz

Continuous reaction (high T to low T): Ca-rich plagioclase feldspar to Na-rich -> K feldspar, muscovite, quartz

28
Q

Fractional crystallization

A

Produces progressively more felsic magmas as a result of crystal settling

  • The first minerals to form are the densest and settle to the bottom of the magma chamber (mafic + others)
  • Produces layered intrusions with some layers rich in useful minerals: chromium, nickel, and platinum
29
Q

Which metamorphic processes create mineral resources?

A

Metamorphism occurs when a rock is subjected to increasing heat and pressure, resulting in recrystallization of minerals (NO MELTING)

  1. Regional
  2. Contact
30
Q

Regional Metamorphism

A

Mountain building produces directed stress

  • Turned shales to slate, schist, and gneiss with increasing metamorphic grade
  • Foliated metamorphic split into slabs (good building material)
  • Can also turn limestone in marble and sandstone into quartzite
31
Q

Contact Metamorphism

A

Metamorphism around a hot intrusion

  • Marble, quartzite used as building materials
  • Also produces skarns: Ca-bearing silicate rocks that commonly contain valuble ores, form at the contact zone between a felsic igneous intrusion and carbonate rocks due to reactions with heated fluids given off by cooling intrusion or fluids within the country rock
  • Metasomatism: fluids mix in contact zone, dissolve carbonate minerals and convert carbonate rocks into skarn deposits
32
Q

Asbestos

A
  • Fibrous and flexible so it can be spun
  • Incombustible and resistant to biodegradation and has low electrical conductivity (thermal insulation, fire protection)
  • Also causes lung cancer
33
Q

Fluids squeezed out of rock during metamorphism may cause minerals to grow very large

A
  • Garnet is a gemstone used as an abrasive
  • Kyanite is a gemstone used in ceramics
  • Regional metamorphism of ultramafic and mafic rocks in the presence of water can create asbestos (hydration of olivine)
  • Talc: formed from metamorphism of Mg-rich minerals (olivine, pyroxene, amphibole, serpentine) in the presence of CO2 and water
34
Q

Which sedimentary processes create mineral resources?

A

Sedimentation can produce valuable deposits: sand and gravel concentrated by rivers are sources of aggregate for concrete

35
Q

Placer deposits

A

Moving water flushes less dense clay and sand away, concentrating dense minerals such as gold, platinum, and diamonds, at the bottom of river channels

36
Q

Chemical sedimentation can produce mineral deposits through:

A
  1. Direct precipitation due to evaporation
  2. Volcanogenic deposits
  3. Chemical precipitates in marine waters
37
Q
  1. Direct precipitation due to evaporation
A
  • Evaporites
  • Marine (halite, gypsum, etc.)
  • Non-marine (calcium/sodium, carbonates, gypsum, etc.)
38
Q
  1. Volcanogenic deposits
A
  • Vents fluids to the surface
  • Ocean-floor black smokers
  • Massive sulfides
39
Q
  1. Chemical precipitates in marine waters
A
  • Banded-iron formation ores
  • Formed before atmosphere has free oxygen
  • Iron ejected into ocean from underwater hot springs reacted with oxygen produced by cyanobacteria and precipitated as a layer of iron oxides. Bands represent cyclic variation in available oxygen and formed until the ocean became fully oxygenated
40
Q

Chemical weathering promotes mineral enrichment because it leaves behind a residue of less soluble minerals

A
  • Oxisols/laterites are heavily weathered soils that form in hot/humid conditions
  • “ironstones” rich in oxides of iron and aluminum and source of bauxite ore (mined for Al)
41
Q

Secondary enrichment

A
  • Disseminated minerals are often difficult to mine because the ore is so spread out
  • Groundwater percolating downward to water table dissolves, transports and redeposits minerals at the water table, creating a secondary deposit of ore minerals
42
Q

How do meteor impacts create mineral resources?

A
  • The Sudbury Igneous Complex: 2nd largest impact crater in the world
  • Formed 1.85bya by collision with meteor 10-15km in diameter, triggering melting
  • One of the world’s principal sources of nickel and copper ores, with gold and platinum
  • Deposits occur in veins and dikes and as contact-type deposits
43
Q

Origins of Mineral Deposits: Mid-Ocean Ridge

A

Metals: copper and zinc as metallic oxides and sulfides

Deposit type: volcanogenic massive sulfide

44
Q

Origins of Mineral Deposits: Volcanic Arc Basin

A

Metals: Copper, lead, zinc

Deposit Type: Stratabound

45
Q

Origins of Mineral Deposits: Volcanic Island Arc

A

Metals: copper, molybdenum, gold, silver, lead, mercury, tin

Deposit Type: porphyry copper; hydrothermal veins

46
Q

Origins of Mineral Deposits: Granitic Intrusions (Batholiths)

A

Metals: Copper, tungsten, tin, iron, gold, silver, molybdenum

Deposit Type: contact-metamorphic; hydrothermal veins

47
Q

How are mineral resources mined?

A
  1. Dredging
  2. Hydraulic Mining
  3. Open-pit mining
48
Q
  1. Dredging
A

Scooping up earth material under a body of water, for sand and gravel as well as placer deposits

  • Increased erosion to channels and river banks
  • Washes away soil
  • Degrades water quality
  • Damages aquatic and terrestrial ecosystems
49
Q
  1. Hydraulic Mining
A

High-pressure water blasted through a nozzle at hillsides containing alluvial deposits, slurry is run over sluice boxes to remove gold

Processes large volumes of sediment quickly, but leads to major environmental damage:

  • Flushes sediments to streams
  • Promotes flood downstream
  • Clogs irrigation, ruins cropland
  • Addition of mercury aids gold recovery, but if not all mercury is recovered it accumulates in ecosystem
  • Mostly blocked by 1900 by courts
50
Q
  1. Open-pit mining
A

Practical way to extract low-grade, near-surface ore bodies, process enormous amounts of mineral

  • Major disruption to landscape
  • Increased erosion
  • Leaching of toxic metals
  • Acid mine drainage