Witherite is a relatively rare barium carbonate mineral that shows a blue/white fluorescent response under short and long wave UV. The historical fluorspar (fluorite) mines of Cave-In-Rock, Hardin County, Illinois, have produced specimens of witherite of exceptional quality. This specimen consists of a mass of large, twinned (pseudohexagonal) crystals of off-white witherite on a minimal matrix of unknown grey material. The witherite shows a similar fluorescent response under all UV wavelengths- glowing blue/white, slightly warmer under long wave. This specimen also shows green phosphorescence, most brightly following short wave UV. The size of this piece is 75 x 71 x 49 mm, and it weighs 302 grams.
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