The government let the mines to contractors for forty years and then took them over; but in the period from 1720 to 1840 only 14,620 tons of galena were extracted and 2772 of lead.
The most important minerals are lead and zinc, obtained in lodes in the forms of galena and calamine respectively.
Galena is found in small quantity, and in some places it contains a large percentage of silver.
Galena and other lead ores are abundant in veins in the limestone, but they are now only worked on a large scale at Mill Close, near Winster; calamine, zinc blende, barytes, calcite and fluor-spar are common.
Galena and other lead ores are abundant in veins in the limestone, but they are now only worked on a large scale at Mill Close, near Winster; calamine, zinc, blende, barytes, calcite and fluor-spar are common.