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The Geosphere
hand, heterogeneous rocks are made up of a variety on
minerals. For example, granite is made up of quartz, feldspar
and mica. Coal and petroleum are exceptions because they
are not of mineral origin.
18.
Listen and identify the rocks: igneous, sedimentary or
metamorphic.
Audio script and answers:
a) These are formed when rocks are subjected to high
pressure conditions. (metamorphic)
b) These originate when the magma cools. (igneous)
c) These form when sediments consolidate. (sedimentary)
Analyse
19.
Study the photo. What type of rock is a conglomerate?
Is it homogeneous or heterogeneous? Explain your
answer.
A conglomerate is a sedimentary rock that is clearly visible. It
is made up of other rocks as well as sediments. Fragments of
a heterogeneous rock are visible and distinguishable with the
naked eye.
Understand
20.
Explain why crystals in the minerals that make up
plutonic rocks are visible, but are not visible in the
volcanic rocks?
Because plutonic rocks are formed during a very slow process
so mineral crystals have more time to form. On the other
hand, volcanic rocks are formed when magma rises and
leaves the Earth’s crust as lava. And lava cools quickly so there
is no time for the crystallisation.
