CVS4, Fig. 8.1 Copper Nickel Cobalt Lead Zinc Chromium Tin Mercury Gold Silver Platinum Rare-earth elements Geochemically scarce

Pure calcite, CaCO 3 Cobaltian calcite, (Ca,Co)CO 3 Solid Solution = Atomic Substitution

Atomic Substitution in Al 2 O 3, Corundum Ruby Sapphire Cr 3+ Al 3+ Fe 2+ + Ti 4+ 2Al 3+ Structure of corundum Images from Wikipedia Gemstones

Geochemistry Meets Economics CVS4, Fig CVS3, Fig. 8.2 CVS4, Table 8.2 Crustal abund. Enrich- ment Minable grade ppm (from ore)

Typical Types of Minerals that are Ores of Geochemically Scarce Metals Dominated by sulfides, oxides, and native metals CVS4, Table 8.3 Base- metal sulfides Alloy- and specialty-metal oxides Native-element precious metals Platinum- group metals

CVS4, Fig. 8.16

Precipitation by Hot Waters Groundwater heated by igneous intrusion. Local heat source creates convection currents in the water. Leaching and pptn. As in porphyry copper deposit CVS4, Fig. 8.20

Porphyry copper deposits are clustered along coasts, above subduction zones. Porphyry Copper Deposits of the World CVS4, Fig. 8.21

education/curr_p1_11.html More Hot Water scienceblogs.com/highlyallochthonous/2 007/07/precambrian_black_smokers.php Black smoker on the sea floor near mid-ocean ridge and rift Copper, iron, and zinc sulfides precipitated in smoker “chimneys”

Cooler Waters (around 100°C) Waters compressed out of sediments in a basin can move, leach metals, and precipitate minerals elsewhere. CVS4, Fig. 8.24b

Lead-Zinc Deposits from Cool Waters About 2 hrs. south of St. Louis CVS4, Fig. 8.24a

Even Colder Water: Ambient Temperature Density separation and concentration of minerals by the flow of (river) water CVS4, Fig Examples = gold, diamonds

South African Gold Deposits: Ancient Streams and Deltas CVS4, Fig Discovered by two prospectors in 1886

Mineral chromite

CVS4, Fig Growth in the copper industry (and use of copper) was spurred by the spread of electrification (copper wire)

Heat copper sulfide mineral Drive off sulfur gas (leaving metal behind) Trap sulfur gas BEFORE it reaches atmosphere. Learn from nature how microbes help to break down sulfide minerals and release metal

From De Re Metallica (1558). Ancient metallurgists attempting to “win” various metals from their ore minerals by heating them.

CVS4, Fig. 8.23

CVS4, Fig. 8.2 Average grade (wt.% Cu) of copper ore mined in the U.S. over time.

CVS4, Fig. 8.31Average grade of gold ore mined in the US over time ~ 1 ppm