Geological Sciences 100

EARTH SYSTEM I:
GEOLOGICAL ENVIRONMENT

Lecture XXIV. Mineral Resources

A) Igneous Ore Deposits	B) Metamorphic Ore Deposits
C) Sedimentary Ore Deposits

A) Igneous Ore Deposits

Figure 24.1 Illustration of the relationship between a parent igneous body and the associated pegmatite and hydrothermal deposits (from The Earth - An Introduction to Physical Geology (2nd ed.), by Tarbuck & Lutgens, Merrill Publishing Co., 1984).

magmatic segregation

Figure 24.2 Chromite beds along the Dwars River (South Africa) on the east flank of the Bushveld Complex.

Figure 24.3 Chromite beds along the Dwars River (South Africa) on the east flank of the Bushveld Complex.
hydrothermal solutions ==> pegmatites, veins, disseminated ores

Figure 24.4 Fluorite veins (Jamestown district, Boulder Co., CO).

Figure 24.5 Pegmatite along highway 6 west of Golden, CO.

Figure 24.6 Veins of gold.

Figure 24.7 Stockwork of molybdenum from Hall Mine north of Tonopah, NV (Anaconda)

Figure 24.8 Open pit molybdenum mining (Climax Moly Corp Mine, Climax, CO).

Figure 24.9 Tailings 1/4 filled slurry pipe below Climax, CO.

Figure 24.10 Tailing "ponds" below Climax, CO.

Figure 24.11 Concentration of ore deposits by weathering processes ==> secondary or supergene enrichment.

Figure 24.12 Morenci open pit porphory copper mine (AZ).

Figure 24.13 Bingham Canyon (UT) open pit porphory copper mine - one of the largest man-made excavations in the world.

Figure 24.14 Tailings "front" from Bingham Canyon (UT) open pit porphory copper mine.

Figure 24.15 Kennicott copper ore smelter along shore of Great Salt Lake (UT).

B) Metamorphic Ore Deposits

Figure 24.16 Origin of metallic mineral deposits.

contact alterations (e.g., precious minerals, metals)
regional alterations (e.g., talc, graphite, asbestos, slate, marble, quartzite)

C) Sedimentary Ore Deposits

evaporite deposits

Figure 24.17 Succession of compounds precipitating from seawater. CaCO2 is precipitated first when evaporation reduces the volume to 19%. CaSO4 begins to precipitate at 9.5%, NaCl at 4%, and so on. Sizes of triangles represent relative proportions of the dissolved salts.

Banded Iron Formations (BIF)

Figure 24.18 Banded (and folded) iron formation from iron mine in Atlantic City, WY (US Steel).

Figure 24.19 Blasting out iron ore from iron mine in Atlantic City, WY.

Figure 24.20 Hauling iron ore at Republic, MI.

Figure 24.21 Tailings from iron ore mining in Republic, MI.

Figure 24.22 Tailings delta into Lake Superior from Reserve (Fe) Mining Co. plant along Minnesota shore. This delta contaminated Lake Superior with asbestos all the way south to Duluth, MN.

Figure 24.23 Reserve (Fe) Mining Co. plant (Minnesota shore of Lake Superior).

strip mining

Figure 24.24 Coal strip mining scars between Champaign and Chicago, IL.

Figure 24.25 Sand mining by Penn. Glass and Shard Corp. near Columbia, SC.

Figure 24.26 Clay pit near Deep Step, GA.

placer deposits

Figure 24.27 Origin of placer deposits.

Figure 24.28 Glacial gravels from gold placer mine near Alma, CO.

Figure 24.29 Excavation and hauling equipment for gold placer mine near Alma, CO.

Figure 24.30 Front end loader excavating glacial drift at gold mine near Alma, CO.

Figure 24.31 Centrifuge and mercury traps where gold can be separated from "grizzly" because it adheres to the mercury.

Figure 24.32 Front end loader dumping 'grizzly" onto sieve where the finer materials will be flushed into the centrifuge with water (gold placer mine near Alma, CO).

Figure 24.33 Flushing 'grizzly" through sieve at the gold placer mine near Alma, CO.

Figure 24.34 Sieve and belt disposal system at the gold placer mine near Alma, CO.

Figure 24.35 Sluices and belt disposal for large boulders at the gold placer mine near Alma, CO.

Figure 24.36 Sluices (60') at the gold placer mine near Alma, CO.

Figure 24.37 Large and small riffles in sluices at the gold placer mine near Alma, CO.

Figure 24.38 Wires and plates of gold in quartz.

weathering/supergene enrichment

Figure 24.39 Concentration of ore deposits by weathering processes ==> secondary or supergene enrichment.

Figure 24.40 Open pit copper porphory mine showing Cu-staining in bottom near Butte, MT.