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!