MINERAL DEPOSITS
HOW, WHERE, WHEN, AND WHY HERE
Jim Miller, University of Minnesota Duluth
MINERAL DEPOSIT IQ TEST
1) What is the main use for Nickel?
Stainless Steel
MINERAL DEPOSIT IQ TEST
2) What is the main use quartz (silica)
sand?
Glass-making
MINERAL DEPOSIT IQ TEST
3) What is the main use for palladium?
Catalytic Converters
MINERAL DEPOSIT IQ TEST
4) What country is referred to as the
“Jewelbox of the World”?
South Africa
MINERAL DEPOSIT IQ TEST
5) What is the principal commodity
needed to make Rayon, Polyester and
other synthetic fabrics?
Petroleum
MINERAL DEPOSIT IQ TEST
6) What is the only thing in this room
that is not grown on or mined from
the Earth?
Sunlight
MINERAL DEPOSIT IQ TEST
7) How much copper is in a mediumsized wind turbine?
 A) 15,000 lbs
 B) 9,000 lbs
 C) 6,500 lbs
 D) 2,000 lbs
 E) 400 lbs
MINERAL DEPOSIT IQ TEST
8) Chile produces the most (1/3rd) of
the world’s copper; which country is
the second largest producer of
copper at 8%?
United States
MINERAL DEPOSIT IQ TEST
9) What is the average percentage of
platinum in the Merensky Reef deposit
of South Africa ?
 A) 10%
 B) 1%
 C) 0.1%
 D) 0.01%
 E) 0.0001%
MINERAL DEPOSIT IQ TEST
10) What percentage of mineral deposit
prospects become mines?
 A) 50%
 B) 10%
 C) 5%
 D) 1%
 E) 0.1%
Terminology and Definitions
Natural Resources – materials, and energy that occur naturally
within the Earth’s spheres. Many are essential for our survival,
while others are used for satisfying our wants.
Biological Resources
• renewable
• recycleable
• reuseable
Wind and Solar
• unlimited
Stuff
Water Resources
• unlimited
• recycleable
• reuseable
Mineral Resources
• non-renewable
• recycleable
• reuseable
“Sustainable Development is development that meets the needs of the present
without compromising the ability of future generations to meet their own
needs” (1984, United Nations Commission)
Stewardship - “administration, management, control, including responsible use
of resources” (Oxford English Dictionary Online)
Mineral Deposit Terminology
Ore – rock whose value of metals exceeds the cost of extracting
them by mining and processing
Grade – percentage of a particular metal in ore rock
Prospect – a mineral occurrence that preliminary investigations
indicate a possibility of a significant resource
Resource – tonnage of ore in such form, quality and quantity that
there are reasonable prospects for eventual economic extraction
Inferred Resource is that part of a mineral resource for which tonnage,
grade and mineral content can be estimated with a low level of
confidence.
Indicated Resources are economic mineral occurrences that have been
sampled to a point where reasonably confident estimate can be
made of their contained metal, grade, tonnage, shape and physical
characteristics
Reserves - are resources known to be economically feasible for
extraction.
How?
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Most rocks on earth contain some amount of metals, but
metal concentrations are so low (parts per billion - ppb), as to
not be considered ORE.
Ore deposits form in under special geological circumstances
and processes whereby metals are concentrated to economic
grades.
Economic concentrations of metals are created by primary
processes (those related to the rock in which they occur) and
secondary processes (those unrelated to the origin of the host
rock).
In most ore deposits, sulfur &/or oxygen are the main anions (charged ions) that concentrate metal cations; other metalbonding anions include As, Bi, Te, CO3, Cl, …
How?
How?
Most Base Metals are concentrated by
Sulfur
Chalcopyrite
CuFeS2
Chalcocite
Cu2S
Pentlandite
(Fe,Ni)9S8
Cinnabar
HgS
Bornite
Cu5FeS4
Sphalerite
ZnS
Molybdenite
MoS2
Galena
PbS
Cobaltite
CoAsS
HOW?
Formation of PGE deposits by sulfide liquation
HOW?
Sulfur Contamination creating the Cu-Ni-PGE Sulfide
Deposits of the Duluth Complex
S
Cu
Ni
S
Co
Pd + Pt + Au
HOW?
New Processing Technology for Sulfide Ores
OLD –
Smelting/
Roasting
NEW –
Hydrometallurgy with
High Pressure Autoclaves
HOW?
The Challenge – Acid Rock Drainage
2FeS2(s) + 7O2(g) + 2H2O(l) →
2Fe2+(aq) + 4SO42-(aq) + 4H+(aq)
Where?
Where/When?
Buried too Deep
Just Buried
When?
Archean Komatiite Flows with Ni-sulfide Mineralization
Evidence of an Early Hot Mantle
When?
Inconvenient Truth #3
Archean Paleo-placer U deposits
Evidence of an Anoxic Atmosphere
When?
Inconvenient Truth #3
Porphyry Cu Deposits
preserved in young mountain belts
When?
Land plants take root on land
about 350 Ma  COAL!
Peat
Anthracite
Bituminous
Coal
Anthracite
Coal
When?
Inconvenient Truth #3
Porphyry Cu Deposits
preserved in young mountain belts
gone
Why Here?
Inconvenient Truth #3
Why Here?
Inconvenient Truth #3
Why Here?
BECAUSE MOTHER EARTH SAID SO!
Mineral Resource Information
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US Geological Survey Commodity Information
http://minerals.usgs.gov/minerals/pubs/commodity/
US Geological Survey Mineral Resource Database
http://mrdata.usgs.gov/mrds/
Minerals Education Coalition
http://www.mineralseducationcoalition.org/
Society of Mining, Metallurgy and Exploration (SME)
http://www.smenet.org/
Prospectors and Developers Association of Canada
(PDAC) – Mining Matters Educational Initiative
http://www.pdac.ca/mining-matters
Lesson Plan Ideas for
Mineral Deposits
How to make a lightbulb?
Objective: An important element in promoting stewardship of our earth resources is to educate
students about what earth resources are involved in the making of everyday things. We will use
manufacturing of a lightbulb to illustrate this point.
Exercise: You are an environmentally conscientious entrepreneur who want to build a compact
fluorescent lightbulb factory in Minnesota. One of the most important decisions is to figure out
what materials you need and where to get them. Cost is a function of distance and the country
supplying the material. Third world countries provide cheaper prices, but are notorious for poor
environmental standards in mining and low wages.
Procedure: You will be assigned an earth resource that is needed to manufacture a CFL light bulb.
Using the USGS and MII websites, research the following information on your assigned resource.
Geologic occurrence (host rock, geological environment)
Enrichment process (primary or secondary?)
Age of occurrence
Imports (% of US consumption)
•Alternative Materials
•Other interesting Information