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Minerals and Rocks
Unit 9
Minerals
• A mineral is a naturally
occurring solid formed through
geological processes that has
a characteristic chemical
composition, a highly ordered
atomic structure, and specific
physical properties.
–
Minerals are not made by
humans. Nature and its processes
form minerals.
– Minerals are solid substances.
Minerals can´t be liquids or
gases.
Chemical Composition
• Minerals have a characteristic
chemical composition. They
always have the same
composition. If its composition
changes, we haver another
mineral. Pyrite in all the world
is an iron sulfide.
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Minerals have a highly ordered atomic
structure. The compounds forming
minerals, called atoms, are ordered
with a geometrical pattern. Not
ordering, not mineral.
Minerals have specific physical
properties(colour, shape,lustre,
cleavage, hardness) This properties
are close related with their structure.
MINERALOGY
Minerals are used in everyday life:
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The salt we put in our food is the
mineral halite.
Our pencil is made of graphite.
Our digital watch can be made using
quartz, aluminium, gold or silver.
Cement is made from calcite.
Plaster is made of gypsum.
– The study of minerals is called
mineralogy.
Rocks
•
•
•
A rock is an aggregate of minerals
and need not have a specific
chemical composition.
Some rocks are made of a single
substance. They are called
monomineralic rocks.
Rocks are divided into three main
classes:
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.
Igneous
Sedimentary
metamorphic.
IGNEOUS ROCKS
• Igneous rocks are
formed fron cooled
magma. Magma is
molten rocky
material below the
Earth`s surface.
– Granite
– Basalt
– Obsidian
SEDIMENTARY ROCKS
• Sedimentary rocks are
formed by the
accumulation and
compaction of sediment,
for example,
– Conglomerate,
– Limestone
– Coal.
METAMORPHIC ROCKS
• Metamorphic rocks
are formed from
other rocks by the
effects of heat and
pressure, without
melting.
– Slate
– Marble.