Feldspar

2 definitions found

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

  Feldspar \Feld"spar`\, Feldspath \Feld"spath`\, n. [G.
     feldspath; feld field + spath spar.] (Min.)
     A name given to a group of minerals, closely related in
     crystalline form, and all silicates of alumina with either
     potash, soda, lime, or, in one case, baryta. They occur in
     crystals and crystalline masses, vitreous in luster, and


     breaking rather easily in two directions at right angles to
     each other, or nearly so. The colors are usually white or
     nearly white, flesh-red, bluish, or greenish.
     [1913 Webster]
  
     Note: The group includes the monoclinic (orthoclastic)
           species orthoclase or common potash feldspar, and the
           rare hyalophane or baryta feldspar; also the triclinic
           species (called in general plagioclase) microcline,
           like orthoclase a potash feldspar; anorthite or lime
           feldspar; albite or soda feldspar; also intermediate
           between the last two species, labradorite, andesine,
           oligoclase, containing both lime and soda in varying
           amounts. The feldspars are essential constituents of
           nearly all crystalline rocks, as granite, gneiss, mica,
           slate, most kinds of basalt and trachyte, etc. The
           decomposition of feldspar has yielded a large part of
           the clay of the soil, also the mineral kaolin, an
           essential material in the making of fine pottery.
           Common feldspar is itself largely used for the same
           purpose. Feldspathic

From WordNet (r) 2.0 [wn]:

  feldspar
       n : any of a group of hard crystalline minerals that consist of
           aluminum silicates of potassium or sodium or calcium or
           barium [syn: {felspar}]