May 3, 2012 by Esther Inglis-Arkell @ io9
These feather-like crystals are both ingested by humans for health and used by them to scrub floors and get the gunk off tiles. Take a look at what they are, and why polarized light makes them look so amazing.
The picture above is citric acid crystals, viewed through a polarization microscope. Everyone reading this has had either citric acid or scurvy sometime in their life. Citric acid, as you might imagine, is in most citrus fruits, as well as a few berries, is used by companies as a way to serve Vitamin C, and is the powder that you see on the outside of sour balls and other sour candy. The acid also dissolves a lot of grime, and thus is used in household cleaners, which is why many cleaners contain ‘lemon oil.’ It’s a useful molecule, but who expected that it could be prettied up?
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