Colorful Fluorite in blues, amber and purples! Many have an amber core then a layer of blue or purple fluorite, often with crystal inclusions of chalcopyrite or other minerals. Crystal growth structures can be clearly seen.
From Hardin County, Illinois and Cave-in-Rock - classic fluorite localities!
Hopper crystals, octogons and cubes Fluorites from the Anna Belle Mine and Minerva #1 Mine, Hardin County, Illinois