A sedimentary rock composed of the shells of diatoms etc., used for polishing.
User Defined Definitions
"a weathered and decomposed siliceous limestone; in powdered form it is used in polishing"
"the capital and chief port and largest city of Libya; in northwestern Libya on the Mediterranean Sea; founded by the Phoenicians in the 7th century BC"
"a port city and commercial center in northwestern Lebanon on the Mediterranean Sea"