agate

from WordNet (r) 3.0 (2006)

agate
    n 1: an impure form of quartz consisting of banded chalcedony;
         used as a gemstone and for making mortars and pestles

from The Collaborative International Dictionary of English v.0.48

Agate \A*gate"\, adv. [Pref. a- on + gate way.]
   On the way; agoing; as, to be agate; to set the bells agate.
   [Obs.] --Cotgrave.
   [1913 Webster]

from The Collaborative International Dictionary of English v.0.48

Agate \Ag"ate\, n. [F. agate, It. agata, L. achates, fr. Gr. ?.]
   1. (Min.) A semipellucid, uncrystallized variety of quartz,
      presenting various tints in the same specimen. Its colors
      are delicately arranged in stripes or bands, or blended in
      clouds.
      [1913 Webster]

   Note: The fortification agate, or Scotch pebble, the moss
         agate, the clouded agate, etc., are familiar varieties.
         [1913 Webster]

   2. (Print.) A kind of type, larger than pearl and smaller
      than nonpareil; in England called ruby.
      [1913 Webster]

   Note: This line is printed in the type called agate.
         [1913 Webster]

   3. A diminutive person; so called in allusion to the small
      figures cut in agate for rings and seals. [Obs.] --Shak.
      [1913 Webster]

   4. A tool used by gold-wire drawers, bookbinders, etc.; -- so
      called from the agate fixed in it for burnishing.
      [1913 Webster]

from The Collaborative International Dictionary of English v.0.48

Chalcedony \Chal*ced"o*ny\ (k[a^]l*s[e^]d"[-o]*n[y^] or
   k[a^]l"s[-e]*d[-o]*n[y^]; 277), n.; pl. {Chalcedonies}
   (-n[i^]z). [ L. chalcedonius, fr. Gr. CHalkhdw`n Chalcedon, a
   town in Asia Minor, opposite to Byzantium: cf. calc['e]doine,
   OE. calcidoine, casidoyne. Cf. {Cassidony}.] (Min.)
   A cryptocrystalline, translucent variety of quartz, having
   usually a whitish color, and a luster nearly like wax.
   [Written also {calcedony}.]
   [1913 Webster]

   Note: When chalcedony is variegated with with spots or
         figures, or arranged in differently colored layers, it
         is called {agate}; and if by reason of the thickness,
         color, and arrangement of the layers it is suitable for
         being carved into cameos, it is called {onyx}.
         {Chrysoprase} is green chalcedony; {carnelian}, a flesh
         red, and {sard}, a brownish red variety.
         [1913 Webster]

from Easton's 1897 Bible Dictionary

Agate
(Heb. shebo), a precious stone in the breast-plate of the high
priest (Ex. 28:19; 39:12), the second in the third row. This may
be the agate properly so called, a semi-transparent crystallized
quartz, probably brought from Sheba, whence its name. In Isa.
54:12 and Ezek. 27:16, this word is the rendering of the Hebrew
cadcod, which means "ruddy," and denotes a variety of minutely
crystalline silica more or less in bands of different tints.

  This word is from the Greek name of a stone found in the river
Achates in Sicily.