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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 B uilding Blocks of Minerals.
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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