Geochemically
Scarce metals
For information and
statistics on many metallic and non-metallic resources, check out the mineral
commodity summaries on the US Geological Survey web site at http://minerals.usgs.gov/minerals/pubs/mcs
Base
(non-ferrous) metals
Copper (Cu)
Properties and use
Red color, malleable,
ductile. Hight thermal and
electrical conductivity. Thus,
major modern use is in electrical wiring.
Important for a long time
in coinage – including all current American coins.
Alloys:
bronze = copper + tin
– castings, bearings
brass = copper +zinc
– decorative items, fittings, castings,
Ore deposits and
mining
Can occur as native
metal, but most common ore minerals are sulfides: chalcopyrite, chalcocite, bornite, digenite, enargite.
Hydrothermal deposits the
most common. Vein deposits occur, but are not important at present.
Skarn deposits . Hydrothermal fluids react chemically
with limestones and deposit minerals (metasomatic type deposit)
Porphyry copper
deposits. Disseminated, low grade, but
gigantic-scale mineraliztion in volcanic rocks. US Cordillera, Chile
Volcanogenic massive
sulfide deposits. Submarine hydrothermal vents at both
divergent and convergent plate boundaries. Includes “Kuroko” deposits in felsic volcanic
domes. Cyprus
Sediment-hosted
stratiform deposits. Usually in clastic sequences,
deposits occur in copper mineral rich shales. Origin uncertain, may have something to do with
volcanic hydrothermal processes.
Zambia, Congo
Magmatic segregation
deposits. Sudbury, Ontario, Canada. Sufides. Nearly always occurs with
nickel.
Processing
Smelting easy, no high
temperatures required. As most
ores are sulfides, SO2 pollution is a concern.
Production and
producers
Widely produced (60
countries). Cheap at present
(so much production because copper deposits well known and easy to find).
Western N and South
America. Chile a major
producer
LEAD
(P b)
Properties and use
Dark grey color. Very ductile and malleable. Dense. good conductor of
electricity. Low melting
point. Toxicity problems
Used extensively by
Phoenicians and Romans for drinking vessels, pipes (hence “plumber”
from plumbum – Latin for lead).
Modern day usage:
lead-acid storage batteries, radiation shielding, solder, paint (although less
common at present), glass manufacture.
No longer a gasoline additive.
Ore deposits and
mining
Main ore mineral galena
Hydrothermal:
Vein deposits
Mississippi Valley type
(MVT) deposits. West of
Appalachians Always in limestones.
Volcanogenic massive
sulfide deposits
Sediment hosted
stratiform deposts
Processing
Extremely easy to smelt
(low melting point).
Production and
producers
As with copper, easy to
find
China. Australia, US,
Peru
High degree of recycling
(also reduces contamination)
ZINC (Zn)
Properties and use
Soft, white metal when
fresh, but dull grey when oxidized.
Used mainly for corrosion
protection of steel – galvanizing.
Galvanizing is a hot dipping process.
Bronze.
Detailed castings for
various machines
In its oxide form: paint
and pigments, ointments and creams.
(Inner part of a US
“penny”)
Ore deposits and
mining
Main mineral sphalerite
(a sulfide); rest as for lead
Processing
As for lead
Production and
producers
As for lead, plus Canada
CADMIUM
Properties and use
Anti corrosion by
electroplating
Pigments
Alloys
Batteries
Some concerns about
toxicity
Ore deposits and
mining
As for zinc
Processing
As for zinc
Production and
producers
As for zinc
TIN
(Sn)
Properties and use
In use for over 5000
years as bronze. Bronze produced
by smelting copper and tin ores together, but not immediately recognized as a
separate metal.
Lead + tin = solder. Used in electronics. Principal current use (35%)
Corrosion control of
steel, tin plate, particularly cans for food.
Lead + tin = pewter
Ore deposits and
mining
Cassiterite (oxide)
Hydrothermal deposits at
convergent margin volcanaoes:
veins, disseminated, skarns
Placer deposits (easy to
mine) - Malaysia, Thailand, Indonesia
Processing
Production and
producers
Malaysia, Thailand,
Indonesia
At least 40 years