Meerschaum

Webster's Dictionary of the English Language

·noun A tobacco pipe made of this mineral.

II. Meerschaum ·noun A fine white claylike mineral, soft, and light enough when in dry masses to float in water. It is a hydrous silicate of magnesia, and is obtained chiefly in Asia Minor. It is manufacturd into tobacco pipes, cigar holders, ·etc. Also called sepiolite.