Industrial grades of silica sand are characterised by their high content of silica (up to 99%) normally in the form of quartz. Quartz is the most common crystalline form of Silicon Oxide (SiO2) which comprises the two most abundant elements in the earths crust (silicon and oxygen). There are rarer crystalline forms of silica, one of which is called cristobilite which is also a prized industrial mineral. Silica sand is produced from loosely consolidated deposits and from weakly cemented sandstones. Silica is hard, chemically inert and has a high melting point. These are essential qualities for many industrial applications.

Both the chemical and physical properties of silica sands are important in distinguishing them from other sand deposits. As well as having a high silica content they must also be low in impurities such as iron oxide which gives sands their typical golden colour, chromite and clays. The ease by which these impurities can be removed during processing is also an important characteristic.

Silica sands also typically have a narrow grain size distribution usually between 0 to 3mm. The sands have to comply with very tight specifications for particular uses and their quality must be consistent. As a result different grades of silica sand are not usually interchangeable for a particular end use.

Notwithstanding the special properties of silica sand deposits they may also need extensive processing to render them suitable for the proposed end use.

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