Economic Uses of Minerals & Rocks

1
Economic Uses of Minerals Rocks

• Energy Resources, Ores, Gems, and Building
  Materials

2
Our Earth Resources

• Why you must have someone somewhere who develops
  the resources you use every day

3
Our Earth Resources

• Resource
• Physical or virtual entity with utility, value,
  and limited availability
• Ore
• Materials that exist in quantities that can be
  extracted and marketed for a profit
• Major types of ores
• Metallic (ore mineral)
• Nonmetallic (gem, IM)
• Energy
• Water

4
Energy Resources Coal, Petroleum, and Natural
Gas

• Fossil fuel energy resources are the foundation
  of technology-based human societies

US Primary Energy Supply 2009 (US EIA)
5
Oil and Natural Gas Deposits

• Origin
• Organic materials trapped in ocean-bottom
  sediments
• Decompose within the rocks and form hydrocarbon
  liquids (oil and gas)
• Hydrocarbons migrate along and within permeable
  rock layers
• Accumulate in an area that is impermeable - "traps

6
Oil and Natural Gas Deposits in MI

• Reservoir rocks are porous and permeable
• Sandstone, limestone
• Unconventional reservoirs fractured shales

7
Basic Concepts Ore Minerals

• Resource
• Absolute volume of a mineral commodity in
  existence, independent of economics and
  technology
• Reserves or proven reserves
• Known quantity of a resource available (produced
  at a profit)
• Dependant on current economic conditions
  (including demand) and extant technology
• Concentration factor
• Ratio of ore material concentration to average
  crustal concentration
• Mode of occurrence
• A desirable commodity must occur in a mineral
  form that is readily processed to produce the
  commodity
• Associated, unwanted mineral material (gangue)
  and waste after processing (tailings) must be
  considered in economic assessment

8
Basic Concepts Ore Minerals

• Ore deposits require
• Source for metals (or other elements)
• Means of concentrating elements into usable
  quantities
• Types of Ore Deposits
• Magmatic (cumulate, lode, pegmatite)
• Hydrothermal (porphyry, vein, skarn, exhalative,
  epigenetic)
• Sedimentary (placer, BIF, laterite, evaporite)
• Ore Minerals
• Native elements (Au, Ag, Cu, Pt, diamond, sulfur)
• Sulfides and sulfosalts (pyrite, sphalerite,
  chalcopyrite, galena)
• Oxides and hydroxides (magnetite, chromite,
  corundum, hematite, rutile)

9
Magmatic Ore Deposits

• Directly crystallize from magma intrusive or
  extrusive
• Occur as
• Accessory minerals
• Disseminated deposits
• Lode deposits
• Ore in many small veins
• California gold deposits
• Pegmatite
• Felsic plutons late stage crystallization of
  magma
• Rich in incompatible elements Li, Cs, Be, Sn, U

• Cumulates
• Dense minerals settle out in ultramafic magma
  chamber
• Chromite, magnetite, platinum group elements

10
Hydrothermal Ore Deposits

• Involve fluids
• Released from crystallizing magma (felsic
  plutons)
• Occur as
• Widely disseminated vein networks
• Porphyry
• Alteration of country rock by late, hydrothermal
  fluids
• Cu, Mo deposited as sulfide minerals in veins
• Skarn
• Fluid alteration of carbonate country rock during
  contact metamorphism (metasomatism)
• Fe, Pb, Cu, Mo as sulfide or oxide minerals
• Epigenetic
• Ore bodies not physically associated with the
  magmatic body that produced the hydrothermal
  fluids
• Pb-Zn and Au-Sb deposits Upper Mississippi
  Valley lead zinc district

11
Sedimentary Ore Deposits

• Concentration of ore minerals due to
• Weathering (laterite, supergene)
• Sorting due to gravity (placer)
• Chemical precipitation (BIF, evaporite)

• Laterite
• Tropical weathering to a residuum of Fe2O3
  Al2O3
• Preserved in the geological record as bauxite
• Placers
• Dense, heavy minerals become concentrated in
  stream bottoms
• California gold deposits
• Banded Iron formation
• Formed in a O2 poor, early earth atmosphere, gt2
  billion years old
• Fe as hematite

12
Mineral Resources

• In 2000, the estimated value of non-fuel mineral
  production for Michigan was 1.67 billion
• The state rose to sixth in rank among the 50
  states in total non-fuel mineral production value
• Michigan accounted for more than 4 of the U.S.
  total

13
Mineral Resources of Michigan

• Portland cement
• Cement binding agent in concrete
• Made from limestone, clay minerals and gypsum
• Michigans leading non-fuel mineral commodity
• Construction sand and gravel
• Crushed stone
• Magnesium compounds
• Salt
• Limestone

14
Mineral Resources of Michigan

• Iron ore
• Largely extracted from BIF
• Michigan was the nations second leading iron
  ore-producing state in 2000
• Copper
• Native Cu of hydrothermal origin
• Hosted in Precambrian basalt lava flows
• Last mine, the White Pine Mine, closed in 1997