Mining Methods Vary Widely - Mining and the Environment: From Ore to Metal - page 227

compensation, aesthetic visual impacts, increased transportation, noise, vibrations and
dust. Finally with very few exceptions mining of industrial minerals does not attract the
attention of international anti-mining activists. One notable exception is potash mining
which has different processing techniques and tailings than most others industrial mineral
mining operations. Adverse aesthetic impacts are also commonly associated with industrial
mineral extraction, most cities having examples of unsightly scars from clay pits, gravel
pits or aggregate quarries.

Gemstones and Diamonds

Jewels or gemstones are sought for their beauty, durability, and rarity. Beauty may be due
to colour, brilliancy when properly faceted, or other special optical effects. Rarity of course
is a psychological necessity. Much literature on gemstones is available (Ali 2003; Burke
2006; www.casmsite.org ) and the subject is only briel y covered in this text. Diamonds are
undoubtedly the king of all jewels. The primary source of diamonds is kimberlite, a strong
igneous rock that occurs as funnel-shaped pipes that extend deep into the Earth's crust
( Case 5.4 ). Diamond crystals are scattered sparsely through the rock. The high price of dia-
monds makes it economic to follow kimberlite pipes deep into the Earth. Once eroded from
kimberlite, diamond is highly durable, remaining in the sediment in which it may be to
some extent concentrated. It is commonly mined from placer deposits in stream and beach
gravels. Mining of these placer deposits may be by conventional excavation equipment or
dredging. Vacuum devices are operated off the coast of South-West Africa to extract dia-
monds from sea bed placer deposits ( Figure 5.3 ) . Diamond grains are separated from other
minerals by various physical processes, with the i nal sorting carried out manually.

The high price of diamonds
makes it economic to follow
kimberlite pipes deep into the
Earth.

Fossil Fuels

The predominant fossil fuels are coal, petroleum, and natural gas. Coal mining is
addressed in more detail elsewhere in this topic; the environmental impacts of coal min-
ing are similar to those associated with the mining of metalliferous ores. Peat mining, still

CASE 5.4
The Kimberly Diamond Mine in South Africa -
The Largest Excavation by Hand

the workings the more it resembled
the inside of an ant heap. Up to
30,000 men were working day and
night to clear the rubble and rock.
When mining stopped the Big Hole
was about 800 metres deep and
more than 14 million carats of
diamonds have been extracted.

In 1866, Erasmus Jacobs found a small
white pebble on the banks of the Orange
River near Hopetown. The pebble turned
out to be a 21.25 carat diamond. In
1871, an even larger 83.50 carat diamond
was found on the slopes of a nearby
hill, Colesberg Kopje, and led to the fi rst
diamond rush into the area. As miners
arrived in their thousands, the hill disap-
peared, and became known as the Big

Hole. A town, New Rush, was formed in
the area, and was renamed Kimberley on
5 June 1873, after the British Secretary
of State for the Colonies at the time, John
Wodehouse, 1st Earl of Kimberley.
When the miners started to work the
Kimberley diamond pipe, nobody knew
how deep it would go. There seemed to
be no end to the diamonds and people
became unbelievably rich. The deeper

Source: Based on Wikipedia.