SiO2

2 definitions found

From The Collaborative International Dictionary of English v.0.48 [gcide]:

  Silex \Si"lex\, n. [L., a finit, a pebblestone.] (Min.)
     Silica, {SiO2} as found in nature, constituting quarz, and
     most sands and sandstones. See {Silica}, and {Silicic}.
     [1913 Webster]

From The Collaborative International Dictionary of English v.0.48 [gcide]:



  Quartz \Quartz\, n. [G. quarz.] (Min.)
     A form of silica, or silicon dioxide ({SiO2}), occurring in
     hexagonal crystals, which are commonly colorless and
     transparent, but sometimes also yellow, brown, purple, green,
     and of other colors; also in cryptocrystalline massive forms
     varying in color and degree of transparency, being sometimes
     opaque.
     [1913 Webster]
  
     Note: The crystalline varieties include: amethyst, violet;
           citrine and false topaz, pale yellow; rock crystal,
           transparent and colorless or nearly so; rose quartz,
           rosecolored; smoky quartz, smoky brown. The chief
           crypto-crystalline varieties are: agate, a chalcedony
           in layers or clouded with different colors, including
           the onyx and sardonyx; carnelian and sard, red or
           flesh-colored chalcedony; chalcedony, nearly white, and
           waxy in luster; chrysoprase, an apple-green chalcedony;
           flint, hornstone, basanite, or touchstone, brown to
           black in color and compact in texture; heliotrope,
           green dotted with red; jasper, opaque, red yellow, or
           brown, colored by iron or ferruginous clay; prase,
           translucent and dull leek-green. Quartz is an essential
           constituent of granite, and abounds in rocks of all
           ages. It forms the rocks quartzite (quartz rock) and
           sandstone, and makes most of the sand of the seashore.
           [1913 Webster]