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