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2.
MINERALS
Minerals and rocks form part of the Earth’s crust. Since ancient times, humans
have used minerals obtained from the Earth.
In order to understand the definition of minerals we will analyse the description
term by term.
❚
Minerals are
solid substances
. They cannot be liquid or gaseous at room
temperature. This is why mercury is not considered a mineral.
❚
They are
inorganic
. They have not been produced by living things, unlike pearls,
shells or amber.
❚
They are natural. This means they have not been made by humans, like plastic or glass.
❚
They have a
definite chemical composition
. They are composed of chemical
elements that are always combined in the same proportion to create the same
mineral. For example, galena, is a mineral formed by two chemical elements:
sulphur and lead.
❚
They have a
crystalline structure
. This means that the particles are arranged to
form a geometric structure that is repeated constantly. For example, the atoms
of galena are structured to form a cubic shape.
If the arrangement of the mineral particles is visible, we call this a
crystal
.
Crystals need enough time and space to form. In a crystal we can identify the
edges, flat faces and the vertices of its geometrical shape.
Minerals
are solid, inorganic, natural materials. They have a definite chemical
composition and usually have a crystalline structure.
Crystallisation of minerals
Crystalline structure of minerals
galena
Remember
4.
Write a list of the characteristics of minerals in your notebook.
Understand
5.
Look at the two pink quartz roses above. Explain which one had more
space and time to form.
6.
Look at the photo of galena above. Can you say that it is a crystal?
7.
Explain why amber is not a mineral.
8.
Would you classify factory-made diamonds as minerals?
9.
Is water a mineral? Explain your answer.
Apply
10.
Look for the definition of
mineraloide
. Decide if the glass in a window
is a mineral or a mineraloide and explain your answer.
