Nice large pockets of large calcite crystals have been found here.  In the southbound lane on I-49 near mile marker 3.4 or 3.6 a roadcut extends down the hill from the road.  At the bottom of the hill where the cut is low with no overhang are pockets of calcite which may continue producing pockets for a while if the boulders are fractured enough to be moved.  The GPS coordinates are exact, and I will attempt to attach a map that should show where to park (before guard rail) and off the shoulder of the road.

Caution when using picks and hammers on chert as this can cause dangerous projectiles.  Use pry bars and pick axes for leverage in moving boulders.  Calcite clusters also may be scattered in tailings around the immediate area.  Look for a nice luster on the crystals and sometimes a darker color can be desirable. 

Large Calcite Pocket Dig Video in Southwest Missouri: