XL 8
This is a piece of Calcite with veins of Fluorite from the Geronimo Mine, Yuma, Arizona.  Under midwave UV the Calcite is bright orange and the Fluorite is equally bright violet.  The shortwave response is similar but not as bright.  Dimensions are 9 x 7 x 6 inches.  Weight is 21 lbs.  Price: $150.