Definition of silica in English:



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

    • ‘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.’
    • ‘In the fossilisation process, the original organic parts of the shark's tooth are replaced by minerals such as iron pyrites and silica.’
    • ‘The silicate minerals are those that contain silica, a combination of silicon and oxygen.’
    • ‘Precipitation of gold is favoured by similar conditions to those that favour precipitation of silica.’
    • ‘Components such as transistors on microchips are made of inorganic materials, primarily silicon and silicon dioxide.’
    • ‘Soils are generally clay silica of varied depths and exposures.’
    • ‘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 most common minerals are those that contain silicon dioxide in one form or another.’
    • ‘Quartz and sand are composed of silicon and oxygen alone: silicon dioxide, or silica.’
    • ‘Glass is made from silica the most common mineral on the planet and aluminium is the most abundant metal on earth.’
    • ‘The silica and other minerals in the clay vitrify under heat and will not become soft clay again.’
    • ‘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.’
    • ‘Soluble silicates can be obtained by heating alkali metal carbonates and silica.’
    • ‘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.’
    • ‘Cristobalite is a crystalline form of silica that has a diamondlike structure.’
    • ‘For some animals, developing hard shells of silica, or incorporating calcium in bones and teeth, has clear benefits.’
    • ‘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.’


Early 19th century: from Latin silex, silic- ‘flint’, on the pattern of words such as alumina.