Worker Adjustment and Retraining Notification Act (WARN) notices were distributed September 16 by White County Coal, indicating final work days between November 15 and November 29.
The mine will cease production prior to the end of the year, according to the letter.
Alliance has so far not released an official statement outside of the internal WARNs. An impetus for the closure is not yet known, though one White County Coal official told local news station WSIL that market uncertainty is to blame.
The mine, located near Carmi, was first opened in 1980 by Mapco Coal. It produced 2.3 million tons in 2015.