Mining Methods Vary Widely - Mining and the Environment: From Ore to Metal - page 220

Metallic minerals are mined specii cally for the metals that can be extracted from them.
We are all familiar with the most common metals but there are a host of others that play
vital roles in society yet remain virtually unknown.

Ferrous and Ferroalloy Metals
Iron, the main ferrous metal, is the most important industrial metal, since its alloy with
carbon is steel. Iron bearing minerals are found practically everywhere, and a proi t-
able discovery of iron ore is likely to be one of very large size. Manganese is an essential
ingredient in the manufacture of carbon steel. Curiously, manganese metal has no use
of its own as a metal, but as a metallurgical material, it has no substitute. Beside man-
ganese, nickel is the most important ferroalloy, being an essential ingredient in stainless
steel. Sulphide nickel ore often contains chromium, platinum, and cobalt. Serpentine and
lateritic nickel deposits are derived from weathering of ultrabasic rocks and are found in
New Caledonia, Cuba, Australia, Papua New Guinea, the Philippines, and Indonesia.
Chromium, like manganese, is found mostly in non-industrial countries which have little
use for it. Chromium mineralogy is simple: one mineral, chromite, is the only ore (Pearl
1974). Cobalt and vanadium are often produced as by-products of mining for other metals
(uranium in case of vanadium; nickel, silver, or copper mining in case of cobalt).

Iron bearing minerals are found
practically everywhere, and a
profi table discovery of iron ore is
likely to be one of very large size.

Base Metals
The term base metal is used informally to refer to a non-ferrous metal that oxidizes or
corrodes relatively easily, and reacts variably with dilute hydrochloric acid (HCl) to form
hydrogen. Copper is considered a base metal as it oxidizes relatively easily, although it does
not react with HCl. In alchemy, a base metal was a common and inexpensive metal, as
opposed to precious metals. A long time goal of the alchemists, of course never achieved,
was to transform base metals into precious metals, gold and silver. Like ferrous metals,
base metal mining is capital intensive. Copper is a metal with many applications, and apart
from gold, was the i rst metal known to humans. Characteristic signs of copper are the
bright green and blue minerals that stain host rocks. Copper minerals vary widely and lead
and zinc are common associates. The main zinc mineral of economic value is zinc sulphide
or sphalerite (Pearl 1974), containing 57 to 67 percent of zinc. Tin has a restricted distribu-
tion, with a 2000 km belt of tin deposits in Southeast Asia extending from Belitung Island
East of Sumatra, Indonesia through Malaysia, Thailand, and Burma and into China, pro-
duces the majority of the world's tin output.

Base metal mining is capital
intensive.

Precious Metals
The term precious metal is used informally to refer to rare metallic chemical elements
of high economic value. Chemically, precious metals are less reactive than most other ele-
ments, have high lustre, and high electrical conductivity. Historically, precious metals
were important as currency and jewellery, but are now regarded mainly as investment and
industrial commodities. The best-known precious metals are gold (Aurum, Au, in Latin,
or 'shining dawn') and silver (argentum, Ag, in Latin) the brightest of all known metals,
known for their uses in jewellery and coinage ( Case 5.1 ). Other precious metals include
the platinum group metals (platinum - which means 'little silver', ruthenium, rhodium,
palladium, and osmium and iridium - or its alloy osmiridium). Platinum was not known
in Europe until Spanish explorers acquired some platinum objects from South America
(Pearl 1974). Interestingly certain other metals - for example, gallium - although not
termed a precious metal, command higher prices.

Chemically, precious metals are
less reactive than most other
elements, have high lustre, and
high electrical conductivity.