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3. The geosphere
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5.
EXTRACTION OF MINERALS AND ROCKS
Rocks and minerals are extracted from mineral deposits in the Earth’s crust.
The minerals that are of interest to extract are called
ore deposit
. The other rocks and
minerals are referred to as
gangue
.
To locate a deposit,
drill holes
are made with large drills. Cylinders of earth are
extracted and then analysed.
Depending on how deep a deposit is and its accessibility, the extraction can be
superficial or subterranean.
❚
Superficial extractions
: rocks and minerals are extracted from the surface or
not very deep under the surface. This type of extraction has a great impact on the
environment. There are various types:
•
In
opencast mines
, such as those in Riotinto (Huelva), the minerals are not
deep underground. To extract them, they make funnel-shaped
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holes (pits). The
edges are stepped to transport the minerals to the surface.
•
In
quarries
, large rocks are extracted, cut into blocks or slabs. An example are
the marble quarries in Macael (Almería).
•
Gravel
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is extracted from
gravel pits
. These are usually found in or near large
riverbeds. There are many in the Tajo river basin.
❚
Subterranean extractions
: rocks and minerals are located deep within the crust
and are extracted using
underground mines
. Vertical tunnels called shafts are
constructed and horizontal tunnels or galleries called
adits
, to extract the minerals.
Key concepts
❚
A deposit is the place
where minerals or rocks are
extracted.
❚
Extractions are classified
according
to
depth:
superficial or subterranean.
A
deposit
is the place where minerals or rocks are found in sufficient quantity
to make extraction economically beneficial.
Extraction of rocks
Understand
31.
What type of superficial extraction is shown in the picture?
Understand
32.
Explain in your own
words, the difference
betweena subterranean
mine and a quarry.
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gravel
:
amixture of rock fragments
between 2 and 64 mm
4
funnel-shaped
:
conical shape
with wide opening and narrow
opening
