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MINERALS – THE BUILDING BLOCKS OF ROCKS
There are nearly 4000 minerals identified in the Earth’s crust.
Each has an unique chemical composition and internal crystalline structure.
Some rare and some very common
The Building Blocks of Minerals
Elements are the building blocks of minerals.
Most minerals contain more than one element.
There are some with only one element. There are 113 known elements,
but only 92 occur naturally The rest have been created in the laboratory
Elements
Elements are composed of atoms. An atom of an element is the smallest
particle that retains the characteristics of the element.
If the atom is broken apart the resulting characteristics of the element are no longer present.
Atoms
Atoms are composed of: A nucleus which contains:
Neutrons – neutral charged particles Protons – positive charged particles
Electrons Which have a negative charge Orbit the nucleus in energy levels, shells
The number of neutrons of an atom can vary without changing the characteristics of the atom.
The variations in the number of neutrons of a particular element are called Isotopes.
Some elements are stable. The majority of elements however are
unstable, which leads to combining or bonding with other elements.
This bonding leads to three-dimensional crystals called minerals
Bonds
When elements combine it is achieved by: Covalent bonding – where electrons of
combining elements are shared.
Ionic Bonding – where electrons are taken/given away
The bonding of elements is what gives the characteristics of the new material formed This will determine it behaviour It shape or crystalline structure.
Example: Halite ( NaCl ) Sodium is a soft, silvery, potentially explosive
metal Chlorine is a green toxic gas Together they make table salt
Which has a cubic structure Examine table salt and you will see this structure
Of the 92 naturally-occurring elements only 8 make up 98% of the Earth’s crust
Silicates
The majority of minerals contain a combination of these 8 elements.
The most popular combination involves Oxygen and Silicon
This combination is known as a Silicate, SiO2
The silicon-oxygen bond forms a tetrahedron crystal, which is a four sided pyramid
Minerals containing the silicon-oxygen tetrahedron are the most common group of the mineral on Earth. This group includes about 1/3 of all minerals in
the Earth’s crust.
Geologist classify minerals into various groups.
Minerals within the same group have similar characteristics
Mineral Groups
Silicates – silicon oxygen Elements – un-combined elements Carbonates – contain a metal and the
carbonate ion ( CO3-2 )
Oxides – contain a metal and oxygen Sulphides – contain a metal and sulphur Sulphates – contain a metal and the
sulphate ion ( SO4-2 )
Halides – contain a metal and either chlorine, fluorine, iodine or bromine
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