All occupations in connection with mining, other than coal, are prohibited for minors under eighteen years of age except the following:
(A) Work in offices, in the warehouse or supply house, in the change house, and in repair or maintenance shops not located underground.
(B) Work in the operation and maintenance of living quarters.
(C) Work outside the mine in surveying, in the repair and maintenance of roads, and in general cleanup about the mine property such as clearing brush and digging drainage ditches.
(D) Work in or about surface placer mining operations other than placer dredging operations and hydraulic placer mining operations.
(E) The following work in metal mills other than in mercury-recovery mills or mills using the cyanide process.
(1) Work involving the operation of jigs, sludge tables, flotation cells, or drier-filters.
(2) Work of hand sorting at picking table or picking belt.
(3) General cleanup work.
As used in this section, the term "all occupations in connection with mining, other than coal" shall mean all work performed underground in mines and quarries: on the surface at underground mines and underground quarries; in or about open-cut mines, open quarries, clay pits, and sand and gravel operations; at or about placer mining operations; at or about dredging operations for clay, sand or gravel; at or about bore-hold mining operations; in or about all metal mills; washer plants, or grinding mills reducing the bulk of the extracted minerals, and at or about any other crushing, grinding, screening, sizing, washing or cleaning operations performed upon the extracted minerals except where such operations are performed as a part of a manufacturing process. The term shall not include work performed on subsequent manufacturing or processing operations, such as work performed in smelters, electrometallurgical plants, refineries, reduction plants, cement mills, plants where quarried stone is cut, sanded and further processed, or plants manufacturing clay, glass or ceramic products. Neither shall the term include work performed in connection with coal mining, in petroleum production, in natural-gas production, nor in dredging operations which are not a part of mining operations, such as dredging for construction or navigation purposes.