mineral resources & mining
TRANSCRIPT
Mineral Resources & Mining
Eight chemical elements make
up 98.3% of Earth’s crust.
Oxygen
Silicon
Aluminum
Iron
Calcium
Sodium
Magnesium
Potassium
Other elements comprise 1.7% of
Earth’s Crust
Many of these are important to industry
Distribution of these elements is not
uniform across the Earth.
Examples: Ni, Ti, Cr, Cu, Pb, Zn, U,
Pt, Au, Ag, etc.
Ore
If one or more chemical elements occur in
sufficient abundance that they may be mined
for a profit, then the rock is termed an ORE.
Classification of Mineral Resources
• Metallic Mineral Resources
• Abundant (Iron, Aluminum, Magnesium, Manganese,
Titanium)
• Scarce (Copper, Lead, Zinc, Chromium, Nickel, Gold,
Silver)
• Non-Metallic Mineral Resources
• Construction (Sand, Gravel, Clay, Limestone,
Gypsum)
• Agriculture/Industry (Phosphates, Nitrates, Sodium
Chloride, Sulfur)
• Ceramics/Abrasives (Feldspar, Clay, Quartz,
Diamond, Pumice, Garnet, Corundum)
Processes of ore concentration
are related to rock formation.
Rocks are grouped into three major families,
based upon their processes of formation.
Igneous Rocks
Sedimentary Rocks
Metamorphic Rocks
Ore formation by igneous processes
Crystal Settling
Dense minerals crystallizing in magma, settle to
the bottom of the magma chamber
– Ex. – Chromium, Platinum, Nickel, Copper, Lead
Ore formation by igneous processes
Hydrothermal
enrichment
water, superheated by
magma, dissolves
minerals and deposits
them in “veins”
– Ex. – Copper, Gold,
Silver
Ore Formation by Igneous Processes
Lode – many thick mineral veins in a small region – Ex. – The “Mother Lode” during the California gold rush
Hydrothermal Enrichment
Pegmatites – “veins” in rocks
Common form of gold enrichment
Exhalites – Submarine vents of hot, mineral-
rich water
“Black Smoker Chimneys” – hydrothermal vents
Associated with mid-ocean ridges
“Black Smokers”
Sulfide Mine in an Exhalite
Deposit
Ore Formation by Sedimentary
Processes
Placer deposits
Moving water erodes rocks releasing heavy
minerals which settle on the bottom of stream
beds (ex. – gold)
– Ex. - gold
Ore Formation by Sedimentary
Processes
Evaporite deposits
Precipitation of salt in shallow marine basins or
saline lakes (in arid climates)
– Ex. – halite, gypsum, borax
Ore Formation by Metamorphic
Processes
During contact metamorphism, pre-existing
rock is altered forming ores
Ex. – Lead, Copper, Zinc
Prospecting and Exploration
Methods of Discovery: Satellite and Aerial Photography
Remote Sensing
Geological Mapping
Magnetic Mapping
Gravity Mapping
Radioactivity Mapping
Geochemical Sampling
Electrical Sounding Ground-Penetrating Radar
Seismic Methods
– Reflection - Detailed but Expensive
– Refraction - Cheap but Not Detailed
Core Sampling and Well Logging
Economic Factors in Mining
Richness of Ore
Quantity of Ore
Cost of Initial Development
Equipment, Excavation, Purchase of Rights
Operating Costs: Wages, Taxes, Maintenance, Utilities, Regulation
Price of the Product
Will Price Go up or down?
Issues in Mineral Exploitation
Who Owns (Or Should Own) Minerals?
Landowner
Discoverer
Government
Unclaimed Areas:
Sea Floor
Antarctica
Who Controls Access for Exploration?
Remote Sensing vs. Privacy
Types of Mines
Surface
Open pit (Au, Cu)
Quarries (stone, gravel, sand)
Strip mines (coal)
Subsurface (underground)
Placer – dredging (Au)
Seafloor– nodules (Mn, Ni, Fe)
Problems with Mining
Safety
Mine Wastes/Pollution
Hazardous working conditions
Noise
Economic Impact
"Boom and Bust" Cycles
Environmental Problems
Exploration
Construction & Operation
Waste Disposal
Reclamation
Returning the land to
a more natural state
after mining
operations have
ended
Mine Albert, Quebec, before and after
reclamation. Government of Quebec
Economic Implications
Ores are not found everywhere
Some ores are richer than others
Ore distribution is a function of geology
Ore distribution is not equal across the world
Some nations are rich in mineral resources
Other nations have few mineral resources
No nation is self sufficient in mineral resources
Environmental Considerations
Mining leaves holes in the ground
Mining adds unusual quantities of sediment to rivers and streams
Mining exposes minerals to interaction with surface and groundwater, which may contaminate them
Mine waste may be unstable - landslides
Smelting may pollute air and water
Why do we need mines?
We all make choices.
Industrialized societies depend on mineral
resources
Environmental problems must be considered in
extracting wealth from the Earth
Its not Good (environment) vs. Evil (industry)
It’s a compromise, of which, we must make the
best!