NEEP602 Course Notes (Fall 1996)
Resources from Space

Resource Limitations on Earth

Geologic Processes and the Formation of Mineral Deposits

On the Earth:
Surface of the Earth 172K GIF
Interior of the Earth 144K GIF
What is a Mineral Deposit?
Ore Forming Processes 24K GIF
Plate Tectonics and Ores 136K GIF
Ore Forming Processes and Cycles
- Rock Cycle 92K GIF
- Hydrologic Cycle 68K GIF
Geologic Time and Ores

What is an Ore Deposit?

Concentration of minerals
Recoverable at a profit
Dynamic function of economic, engineering, political, and environmental factors

US Bureau of Mines Box
17K GIF

Reserves
- identified geologically and are economic at present
Reserve Base
- reserves plus identified lower quality material
Resources
- reserve base plus any other concentration to be found in the future

Ore Minerals and Ore Forming Processes

Ore mineral
Gangue minerals
Grade
Cut-off Grade
Size of Deposit

Geologic Processes

Surface Processes
- Weathering, Sedimentation (clastic and chemical)
Subsurface Processes
- Actions of Fluids
- Magmas, Brines, Groundwater
- Chemical & Physical Processes

Ex: Surface Processes

Chemical & Physical Weathering
Regolith and Soils
Removal of Soluble Constituents
Redistribution of Material
- Laterites

Ex: Clastic Sedimentary Processes

Beach Sands
Placers
- Gold, Titanium, Magnetite, Uraninite
Paleoplacers
- Ex: Witwatersrand, South Africa

Ex: Chemical Sedimentary Processes

Precipitation from water
Isolated Basins
Evaporites
Marine: Gypsum, Halite, Sylvite
Lacustrine: Trona (sodium salts)
Banded Iron Formations
Sedimentary Exhalative Deposits

Reserve and Resource Estimation

Earth's mineral endowment = Resource
Fraction which has been identified and can be extracted at a profit = Reserve
Estimates of these rely on Geology and Statistics

Geological Estimates

Based on actual observation
Individual deposit data is collected and compiled
Such estimates only give us measured and perhaps indicated reserves
How can we know resources?
Categorize favorable geological environments

Resource Estimation

Particular commodities occur in only certain geological settings
Searches can be focused after or during routine mapping
Can identify probabilities of finding specific settings
This may work with known deposit types but fails for those resources in deposit types not yet known or recognized

Statistical Estimates

Usually hinge on the assumption that the mineral reserve can be treated as a single homogenous population
This allows estimates of the whole to be made from partial information
NO information on the where; only the how much
Several empirical observations have been made

Crustal Abundance Relation

Reserves for some elements exhibit a constant ratio to their average crustal abundance
Reserves for less explored commodities can be estimated from well explored ones
See Fig 13-1 A. for such a plot 9K GIF

Lasky Relation

Logarithmic increase in volume with an arithmetic decrease in grade
Exact ratio varies with deposit type
See Fig 13-1 B for example of Cu 7K GIF

Watch out for Extrapolation!

Infinite resource with infinitely low grade
- Nonsense of course
Neglects energy costs
Assumes that the element/deposit remains the same in different rock types
- Forms own mineral at "high" concentrations
- Substitutes in crystal structure at "low" concs.

Combined Estimates are BEST

Ex: Oil and Gas in the U.S.
Similar data hard to acquire for most metals
Where present, a single country's data is often masked by world wide production

Additional Factors

Stockpiles
- Strategic minerals; definition changes
- Abnormal factor in nominally "free market"
Recycling
- Most perfect form of mineral use
- Not possible with many things however
- (Will be KEY in space)

World Reserves and the Future

Divide reserve figures by present consumption
1992 data shown in Figure 13-5 36K GIF
Some things are in very short supply

Use Reserve Base Instead of Reserves?

Provides a longer term perspective
1 to 5 times more material available than in reserve calculation
However what is the fallacy with this logic?

Population and Standard of Living will Increase Significantly

Therefore present consumption is a minimum for the future
2 to 3 times greater consumption as an average for the next 10-50 years is likely
Maybe twice the time shown in the Table before we run out of certain materials

Additional Problems with this Summary

Source of the numbers: compare early 1980's
RB/P does not tell us the rate at which a commodity can be produced
Doesn't tell us what price is needed to make the reserve base available

Price vs Consumption

Availability can be markedly influenced by price
Fig. 6.1 shows U.S. consumption vs Price 15K GIF
Cut the price by factor of 10 = consumption will increase 20-50 times

How to Forecast Future Production?

Look at past 20-30 years for guidance
16K GIF 9K GIF
Examine and anticipate technological change
How can we anticipate events like the oil embargo?
12K GIF

The Real Significance of these Numbers:

How long to find reserves and put them into production?
Reserves are of no use if left in the ground
Exploration takes a long time
Development can take a long time
Time is Money

How does this apply to Space?

Some rules the same, some different
- "crustal abundances"
- economies of scale
- substitution possible?
- role of recycling
Technological constraints

References and a more complete treatment of mineral resources issues on the Earth can be found in my course Minerals as a Public Problem.

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