Fluorite, Calcite – Minerva No. 1 Mine, Cave in Rock, Hardin Co., Illinois, USA
 Intensely colored fluorite specimen with lustrous crystals of yellow fluorite coated with a dark asphaltite layer. The yellow color of the fluorite is visible in transmitted light.
 A beautiful collector's piece from the well-known site, which is unfortunately no longer in operation and therefore cannot produce new specimens of this beautiful quality.
 The asphaltite layer is usually removed from the fluorites, so this is a rare uncleaned collection piece.