Alum has a huge range of uses, including in industrial synthesis, cosmetics, baking, and taxidermy. It also makes great crystals, which is why it’s the material used in the U.S. Crystal Growing Competition. University at Buffalo chemistry professor Jason Benedict has run the contest for four years. This year more than 4,000 kids will be growing crystals. “We’re really excited because the contest has basically doubled in size since last year,” he says. K–12 contestants receive a 500 g bottle of alum, aka aluminum potassium sulfate, and have five weeks to grow the best crystal they can. Benedict, along with students and collaborators from the University of Central Florida, Georgetown University and Texas A&M University, score the crystals on size and quality. The contest is on twitter: @USCrystalComp.
The big alum single crystal shown is about the size of a plum. In the group shot, the largest is also roughly plum-sized.
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