Availability of the Herrin Coal for mining in Illinois : map summary of Illinois minerals 120

Geology and Minability The 79 billion tons of Herrin Coal remaining in Illinois are the largest coal resource in the state. Although the Herrin has been actively mined since the early 1800s, only slightly more than 10% of the original 89 billion tons of resources have been mined out or left as pillars. The degree to which this remaining resource is utilized in the future depends on the availability of deposits that can be mined at a cost that is competitive with other coals and alternative fuels.