Mineral Party Tricks at the Orange River

To tell you the truth, I never thought much of fluorite. Seems too cutesy to be the favorite mineral of anybody serious. I mean, the formula is dead simple (CaF2) and the name is practically a giveaway for it anyway. It comes in all kinds of luminous colors, any color you want, and cleaves into darling little double-pyramids. Yah, it's pretty, and puppies are cute. Tell me something interesting.

Even in this abandoned mine - really just a half-dug-out vein about 1.5m thick - it's cute. Look at that bright purple and pale green. Fluorite does look great in those black light mineral displays - it fluoresces, it phosphoresces... and some specimens can also thermoluminesce...
My opinion on fluorite changed when my students showed me what you can do with it (but only at night, while camping, and in possession of a mad excess of messy, less pretty handfuls of fluorite chips).

When nobody's looking, toss a handful or a few bigger chunks into the campfire. Best if it's a little low to the coals and not too bright. A few minutes later, long enough for anyone who saw the toss to forget about it, small points of turquoise glow fade into view among the coals. They grow brighter and brighter and then POP! Like a little popcorn kernel the crystal explodes in a tiny shower of blue sparks. A whole handful is enough to emit quite a POP, too.