#silica__silicon_oxide__siliconoxide__silicon_dioxide__silicondioxide  a white or colorless vitreous insoluble solid (SiO2); various forms occur widely in the earth's crust as quartz or cristobalite or tridymite or lechartelierite
  supertype:  oxide  any compound of oxygen with another element or a radical
  substance of:  cristobalite  lechartelierite  quartz  tridymite
  subtype:  chert  variety of silica containing microcrystalline quartz
     subtype:  taconite  a variety of chert containing magnetite and hematite; mined as a low-grade iron ore
  subtype:  flint  a hard kind of stone; a form of silica more opaque than chalcedony
     subtype:  gunflint  the piece of flint that provides the igniting spark in a flintlock weapon
     subtype:  firestone.flint  a piece of flint that is struck to light a fire
     subtype:  flintstone  pebbles of flint used in masonry construction
  subtype:  silex  a pure form of finely ground silica

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