geology introduction to earth

MMPE 290
Introduction to Mining & Mineral Process
Engineering
Mining Geology and Exploration


Mining Geology and Exploration
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How much metal is available?
What is a mineral? What is ore?
How do ore deposits form?
Mining exploration methods
Role of exploration in mining
Case histories


Economically Important
Metal
Concentrations in Earth’s
Crust
Concentration
Metal
Aluminum
Iron
Copper

Nickel
Zinc
Uranium
Lead
Silver
Gold

(% by weight)
8.0
5.8
0.0058
0.0072
0.0082
0.00016
0.001
0.000008
0.0000002

Note for
comparison:
Silicon 28%
Oxygen 46%


What is a mineral?
A
solid
naturally-occurring
compound having a definite chemical
composition

Examples:
quartz - SiO 2 (an oxide)
hematite - Fe 2 O 3 (another oxide)
covelite - CuS (a sulphide)


What is an ore deposit?
An occurrence of minerals or
metals
in
sufficiently
high
concentration to be profitable to
mine and process using current
technology and under current
economic conditions .


What is ore grade?
Ore grade is the concentration
of economic mineral or metal in
an ore deposit.

· Weight percentage (base
metals)
· Grams/tonne or oz/ton
(precious metals)


Economically Important

Metals
Typical Grades of Ore
Deposits
Typical Grade
Metal
Aluminum
Iron
Copper
Nickel
Zinc
Uranium
Lead
Silver
Gold

(% by weight)
30
53
0.5-4
1
4
0.3
5
0.01
0.0001-0.001


What does it take to be an
ore deposit?
2

10

Iron
Aluminum

Typical Orebody Concentration

1

10

Lead Zinc
Copper
Nickel

0

10

Uranium

y=x

-1

10

Silver

-2

10

-3

10

Gold

-4

10

-7

10

-5

10

-3

10

-1

10

Crustal Concentration

1

10

3

10


Hydrothermal Ore
Deposits

As magma cools, more abundant
metals (silicon, aluminum) deposit
first
Solidification of magma releases water
- a hydrothermal solution
Minerals precipitate from
hydrothermal solution and deposit in
cracks or veins in rock


Metamorphic Ore Deposits
Concentration of minerals caused by
high temperatures and pressures
near intrusions
Examples:
Lead-zinc deposits in southeast

B.C.
Diamonds
Garnets


Hydrothermal and
Metamorphic Ore Deposits
Geyser or hot spring

zoning

Hydrothermal solutions
entering veins in rocks

Ore deposit
Alteration of rocks by
heat and pressure

Intrusion


Sedimentary Ore Deposits
Deposition
of
dense,
resistant
minerals
in
streams,
lakes

etc
(Alluvial Deposits),
e.g. Placer
gold
Precipitation
of
minerals
from
ancient oceans (Evaporite Deposits),
e.g. Potash and salt deposits
Accumulation,
burial
and
petrification of vegetation, e.g. Coal
Deposits.


Exploration Methods
· Remote sensing
· Geological mapping
· Geophysical surveys
· Geochemical surveys
· Bulk sampling
· Drilling (core or destructive)


Airborne Geophysics
Helicopter
Bush
Cable

“Bird”


GEOPHYSICAL
METHODS


Geochemical Anomalies






DIAMOND DRILL



DIAMOND DRILL
HOLE SIZES


SURFACE SET
DIAMOND DRILL
CORE BIT AND
REAMING SHELL


Senior Mining Company

Exploration Expenditures - 1997
Total: $817.7M