Prior to that, galena and smithsonite were the dominant minerals produced. Hundreds of mines producing sphalerite are known. All of the mines are currently inactive and most are inaccessible or difficult to find because they have been either overgrown, collapsed, filled-in or leveled. Many of the dumps have been removed for road metal. Still, scattered piles of waste rock persist throughout Grant, Iowa and Lafayette Counties, providing some interesting mineral collecting as well as testimony to the extent and importance of mining in the region.
Common colors are red-brown to dark brown.
Black varieties often bear manganese. Rarer colors of sphalerite noted are red, yellow, grayish blue and deep purple. Partial to complete pseudomorphs of smithsonite after sphalerite are widespread. Heyl, et al. Some sphalerite is found in delicately banded veins featuring gently botryoidal surfaces composed of the tips of small radiating crystals.