The basic building
block of all the
silicate minerals: SiO
4. One
Silicon (Si)
ion bonds with four
Oxygen(O) ions to form a
tetrahedra with the Si at the centre. This bond is very strong, thus silicate minerals are usually hard and have high
melting points.
Overall, the silicon tetrahedra has a
negative charge: this makes it readily
combine with
positively charged ions such as
Iron(Fe) to form minerals, in this case Olivine.
The tetrahedra can also link together to form chain, sheet and framework minerals. The nature of the linking is used to classify silicates and accounts for their physical and chemical properties. For details on the different linkings, see:
Island Silicates
Chain Silicates
Sheet Silicates
Framework Silicates