Chemical Basis for Formation of Ores

1
Chemical Basis for Formation of Ores
Ore a body of rock with a relatively high
concentration of an element

• How do we get a lot of one element in a small
  place?

2
Magmatic Concentration Mainly for abundant
metals
Eutectic Diagrams
3
SublimationMainly just Sulfur
4
Evaporation
Highly soluble salts NaCl, KCl, NaNO3
5
Weathering mechanical concentration

• Rock breaks down, is transported by water, and
  deposited all in one place. Example gold.

6
Weathering Residual Concentration

• Resistance to weathering- single compound left in
  one place.
• Al2O3 deposits formed this way.

7
Bacterial Action Insoluble Sulfide Ores
Sulfate reducing bacteria SO42- carbohydrates
(CH2O) 2 H ? H2S 2 CO2 2 H2O Pb2 H2S
? PbS 2 H