145  Clay, Ceramic, and Refractory Minerals

Establishments primarily engaged in mining, milling, or otherwise preparing
clays and refractory minerals. Mines operated in conjunction with plants
manufacturing cement, brick or other structural clay products, or pottery
and related products, are included in this industry when separate reports
are available. Establishments primarily engaged in grinding, pulverizing,
or otherwise treating clay, ceramic, and refractory minerals not in
conjunction with mining or quarrying operations are classified in
Manufacturing, industry 3295.