Sophia Lai’s favorite structure is:

Bismuth hopper crystals


Source: Top: DeviantArt, Bottom: My own


I made these crystals my junior year in high school and I still have them. I take them out every so often just to marvel at how straight the edges of the intricate square spiral pattern are. If you hold them to the light at different angles, you can see the colors change— a phenomenon known as iridescence. The colors are actually caused by the oxide or tarnish on the surface of the bismuth, which otherwise is a silver metal. Because the thickness of the oxide layer varies, the color varies due to interference between reflected light of different wavelengths. Bismuth forms hopper crystals when re-melted, which are the square spirals you see here. Besides being beautiful, bismuth is a special element with niche uses (medicinal, catalysis, etc). It is the most diamagnetic naturally occurring metal and similar to water, it is denser as a liquid than solid. Because of its strong diamagnetism, you can levitate magnets over a bismuth plate!—Sophia Lai

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