noun

• A hard, unreactive, colourless compound which occurs as the mineral quartz and as a principal constituent of sandstone and other rocks.

  Alternative name: silicon dioxide; chemical formula: SiO₂

  ‘Soluble silicates can be obtained by heating alkali metal carbonates and silica.’

  More example sentences

  • ‘Quartz and sand are composed of silicon and oxygen alone: silicon dioxide, or silica.’
  • ‘Cristobalite is a crystalline form of silica that has a diamondlike structure.’
  • ‘When serpentine dissolves in sulfuric acid, the silicon in the mineral becomes silicon dioxide, or sand, and falls to the bottom, while the magnesium becomes magnesium sulfate.’
  • ‘For some animals, developing hard shells of silica, or incorporating calcium in bones and teeth, has clear benefits.’
  • ‘In the fossilisation process, the original organic parts of the shark's tooth are replaced by minerals such as iron pyrites and silica.’
  • ‘Early in the 1800s, mineralogists recognized that tiger's-eye was a fibrous variety of quartz, or silicon dioxide.’
  • ‘The host limestone surrounding the pockets has been largely replaced by silica and iron oxides.’
  • ‘The silica and other minerals in the clay vitrify under heat and will not become soft clay again.’
  • ‘The silicate minerals are those that contain silica, a combination of silicon and oxygen.’
  • ‘The most common minerals are those that contain silicon dioxide in one form or another.’
  • ‘Glass is made from silica the most common mineral on the planet and aluminium is the most abundant metal on earth.’
  • ‘Precipitation of gold is favoured by similar conditions to those that favour precipitation of silica.’
  • ‘Soils are generally clay silica of varied depths and exposures.’
  • ‘The engines of tomorrow's PCs may be based not on silicon dioxide but on exotic new compounds such as perovskite oxide or even the stuff of life itself, DNA.’
  • ‘Components such as transistors on microchips are made of inorganic materials, primarily silicon and silicon dioxide.’
  • ‘Chert is a finely crystalline silica that commonly forms in association with hot springs.’
  • ‘Silica aerogel is made by mixing silicon dioxide with liquid alcohol, then drying out all the alcohol until you have the least-dense matter on earth: A piece of silica aerogel is 99.6 per cent empty space.’
  • ‘Several powders or dry colours use a base of asbestos, chalk powder or silica.’
  • ‘Sandy soil attached to the furs was the source of silica in the fur dust.’