Definitions

from The Century Dictionary.

  • noun A crystallized form of silica, found in minute transparent tabular hexagonal crystals in trachyte and other igneous rocks, usually in twinned groups, and commonly of three crystals. It has a lower specific gravity than quartz (2.2), and is soluble in boiling sodium carbonate.

from the GNU version of the Collaborative International Dictionary of English.

  • noun (Min.) Pure silica, like quartz, but crystallizing in hexagonal tables. It is found in trachyte and similar rocks.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

  • noun mineralogy A rare mineral of volcanic rocks that solidified at a high temperature, with the chemical composition silicon dioxide, SiO2. Tridymite is chemically identical to quartz, but has a different crystal structure. Sometimes contains sodium aluminum silicate, which seems to be expelled when quartz solidifies at lower temperatures.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • noun a mineral form of silica

Etymologies

from Wiktionary, Creative Commons Attribution/Share-Alike License

The name refers to the peculiar habit of crystallizing in groups of three individuals.

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Examples

  • People will generally be very concerned about the effects of ash, and questions usually arise about the content of the ash, particularly regarding the minerals quartz, cristobalite, or tridymite.

    Volcanic Ash -- Effects on Health and Mitigation Strategies 2009

  • Volcanic ash may contain varying proportions of free crystalline silica (silicon dioxide, SiO2) in the form of quartz, cristobalite, or tridymite minerals.

    Volcanic Ash -- Effects on Health and Mitigation Strategies 2009

  • People will generally be very concerned about the effects of ash, and questions usually arise about the content of the ash, particularly regarding the minerals quartz, cristobalite, or tridymite.

    Volcanic Ash -- Effects on Health and Mitigation Strategies 2009

  • Volcanic ash may contain varying proportions of free crystalline silica (silicon dioxide, SiO2) in the form of quartz, cristobalite, or tridymite minerals.

    Volcanic Ash -- Effects on Health and Mitigation Strategies 2009

  • These other forms of silica include opal, chalcedony, flint and chert (non-crystalline), and cristobalite, tridymite, coesite, and stichovite.

    Quartz 2008

  • Safety Commission [NOHSC] set guidelines for crystalline silica dust as cristobalite, quartz and tridymite as 0. 1mg / m3 respectively.

    unknown title 2009

  • Quartz, tridymite and cristobalite are the three most common types of crystalline silica.

    unknown title 2009

  • But they were surprised to find cristobalite and tridymite crystals, because they require flash-heating events, such as shock waves, to form.

    SPACE.com 2008

  • It is these high-temperature forms of silica crystals, specifically cristobalite and tridymite, that Forrest's team found in planet-forming disks around other stars for the first time.

    SPACE.com 2008

  • It is this high-temperature form of silica crystals, specifically cristobalite and tridymite, that Forrest's team found in planet-forming disks around other stars for the first time.

    Universe Today 2008

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