"This is a Calcite from Bethel Level, Minerva #1 Mine, Cave-in-Rock, Hardin Co., Illinois, USA. Mined in 1994 during pillar-robbing, this attractive piece features knobby, almost stalactitic Calcite (likely stout euhedral crystals underneath) completely covered by sharp Calcite crystals.
Click here for more info on The Arkenstone."