The Collaborative International Dictionary of English v.0.48:

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]

WordNet (r) 3.0 (2006):

silex
    n 1: a pure form of finely ground silica
    2: a vacuum coffee maker

U.S. Gazetteer Places (2000):

Silex, MO -- U.S. village in Missouri
   Population (2000):    206
   Housing Units (2000): 91
   Land area (2000):     0.191724 sq. miles (0.496564 sq. km)
   Water area (2000):    0.000000 sq. miles (0.000000 sq. km)
   Total area (2000):    0.191724 sq. miles (0.496564 sq. km)
   FIPS code:            67808
   Located within:       Missouri (MO), FIPS 29
   Location:             39.122968 N, 91.057371 W
   ZIP Codes (1990):     63377
   Note: some ZIP codes may be omitted esp. for suburbs.
   Headwords:
    Silex, MO
    Silex