This major group includes establishments primarily engaged in mining or quarrying, developing mines or exploring for nonmetallic minerals (except fuels). Also included are primary preparation plants, such as those engaged in crushing, grinding, washing or other concentration:

    144.  Sand and gravel;

    145.  Clay, ceramic and refractory minerals;

    147.  Chemical and fertilizer mineral mining;

    148.  Nonmetallic minerals (except fuels) services;

    149.  Miscellaneous nonmetallic minerals (except fuels). (Prior code § 11-20-013)