CHAPTER 12: Mineral Resources

                sufficiently                             relative to_______ _______________ _______ to make

                it ________________________________worth mining

                                          Conc. metal  in the ore
Concentration factor =  ______________________________
                                      (CF)   conc metal in average cont. crust

larger CF => richer ore => less rock per unit of valuable metal  needs to be extracted
Mineral CF for profilable mining inversely proportional to average crust

abundance.
value                        of the element determine profitability.
concentration

 Profitability depends also on demand, type of ore, politics

Distribution: Ores are unusual: not evenly distributed
             U.S.A.: Mo, Pb (no Al)
             South Africa: Au, Pt

Types of Mineral Deposits (origin)
                          Pegmatites = feldspar, Turmaline, Beryl, Qz
                               coarse grained > 2.5 cm = 1 inch
Igneous              Magmatic: layered intrusions - chromite, magnetite, Pt., gold
                          Kimberlites: diamonds
                          Hydrothermal Ores:

Hydrothermal Ores: Formed from residual (_____ enriched)______ fluids after crystallization of igneous rocks.  How and where do they appear?
______________________________________________________________

As sulfides (__, __, __, Au, Ag)  Pt, U or associated with quartz
 Hydrothermal & igneous deposits obviously related to
                   ____________________________- (magm. activity)

 Where? ______________  _________ ridges
 
 
 
 

Sedimentary Deposits: 
 

• banded iron formations. How did they form?

______________________________________________________________

• Evaporite deposits

 

Placers:           Ores mechanically concentrated by streams or waves on the
Sn Ti Au          the basis of density or resistance to weathering.

Weathering  => forms  bauxite, the ore for ___________
 
 

Metamorphic Deposits
 Graphite = metamorphism of coal
 Asbestos = metamorphism of ferromagnesian silicates. Significance?
 
 
 
 
 
 
 

Minerals                 Metals
                                Non Metals      Sulfur
                                                        evaporites

 Rocks                 sand gravel limestone
                           dimension & facing stones

 U.S. Consumption vs. World Supply & demand (see tables in the text-book)
 
 
 

Minerals for the future: how to increase supply?
 

New methods of Min exploration:

•  Geo__________: based in different density, electrical or magnetic properties - Radioactivity
•  Geochemical: analyzes_____,  plants, _________
•  _______Sensing:  useful in remote areas - sensitive to infrared or green wavelengths - Need sometimes field "check"

 How does Plate tectonics help?:
 
 
 
 
 
 
 
 
 

Marine Mineral Resources

•  Placer shelf deposits (last Ice Age formation)
•  Hydrothermal deposits in ridges
•  Manganese nodules: formed in deep sea

Conservation of Min. Res         1 - substitute?
 

                                                   2 - Recycle (less: land mined, waste, energy)
                                                  need to be quite pure - (alloys = problem)
 
 
 

Impact of Mining:
Underground mining
         problems = _________, local disturbance: around principal shaft

Surface Mines                      open pit: all is used & exposed
                                             strip mining- spoil banks -
 

Land Reclamation
 
 
 
 

Mineral Processing: Tailings: finely divided waste of mines
                             chemicals used in processing minerals are harmful - controls needed

Why are they harmful?
 
 
 
 

How to control?
 
 
 
 
 

CHAPTER 12 - MINERAL RESOURCES
REVIEW QUESTIONS AND TOPICS
1)  Define: resource, reserve, ore, concentration factor.
2   Factors to consider when determining if a mineral deposit is profitable to mine.
3)  Minerals from which the U.S. is an important producer and minerals from which the U.S. is an important consumer or importer.
4)  Classification of mineral deposits according to their origin. Examples of minerals mined from those deposits.
5)  Characteristics and origin of the different kinds of deposits. Pegmatites, magmatic segregations, kimberlites, hydrothermal deposits, banded iron formations (know how and when they were formed), evaporites, placer deposits).
6)  Bauxite: Explain its origin and the element extracted from it.
7)  Origin and uses of graphite and asbestos.
8)  The asbestos myth: Health hazards related to asbestos from the amphibole and sheet silicate groups. Name two asbestos minerals. Rank the health hazards they pose to humans.
9)  What are the principles upon which geophysical methods are based?
11) How can geochemical methods aid in mineral exploration? What materials do you analyze?
12) What type of deposits do you expect to find at midocean ridges? How are they formed?
13)  Problems for the exploitation of manganese nodules.
14)  Substitutions as an alternative to overcome metal shortages.
15)  Advantages and limitations of recycling.
16)  Compare and contrast the enviroirrnental impact caused by underground and surface mining.
17)  Define spoil banks and tailings. What type of problems are related to them? Why do those problems arise?