Mirry Criel, an undergraduate at the University Institute of Technology in Montpellier, made these iodine crystals for her inorganic chemistry course. The apparatus she used (held upside-down in this photo) consisted of a flask with a cooled glass tube hanging inside it. Criel loaded solid iodine in the flask and heated it, causing the iodine to sublime—transition from a solid directly into a gas. Once the gaseous iodine hit the cooled tube, it deposited into a solid again and formed these dark purple crystals.
Submitted by Mirry Criel
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CORRECTION: This story was updated on Feb. 8, 2018, to correct the term for the phase transition from gas to solid. The opposite of “sublimed” is “deposited,” not “condensed.”