1850 53 142 The chief production of San Salvador has been indigo; but..the mineral workings have been considerable.
1880 Apr. 668/2 Another thing that the Indians did was to cover up all the old mineral workings.
1973 C. Callow vi. 133 The Government has backed this up with its own Mineral Workings (Off-shore Installations) Act of 1971. This Act calls for a safety manager on drilling platforms and the keeping of log books.