Name Silicon dioxide
Chemical formula SiO2
Appearance Transparent solid


Formula weight 60.1 amu
Melting point 1986 K (1713 °C)
Boiling point 2503 K (2230 °C)
Density 2.6 ×103 kg/m3
Crystal structure Quartz, cristobalite or tridymite
Solubility 0.012 g in 100g water


ΔfH0gas -305.43 kJ/mol
ΔfH0liquid -899.86 kJ/mol
ΔfH0solid -910.86 kJ/mol
S0gas, 1 bar 228.98 J/mol·K
S0liquid, 1 bar ? J/mol·K
S0solid 41.46 J/mol·K


Ingestion Low hazard.
Inhalation Irritation, long term exposure causes silicosis.
Skin May cause irritation.
Eyes May cause irritation.
More info Hazardous Chemical Database
SI units were used where possible. Unless otherwise stated, standard conditions were used.

Disclaimer and references

The chemical compound silicon dioxide, also known as silica is the naturally occurring oxide of silicon, chemical formula SiO2.

It is found in nature in several forms, including sand and quartz and is also a major constituent of many minerals, including flint.

It is also manufactured in several forms including glass (in colorless high purity form called fused silica) and silica gel. It is a major ingredient of Portland cement.

Inhaling silica dust can lead to silicosis.