• (n.) A refractory material consisting of crushed or ground siliceous stone, mixed with fire clay; -- used for lining Bessemer converters; also used for macadamizing roads.
Gannister is a very siliceous close-grained variety of clay with a poor alkali content found especially under coal seams in the Coal Measures of northern England.
An acid (silicious) refractory often used in furnace linings.