What are Bismuth Crystals?

By Jackie Valentine, Exhibits Experience Lead at the Fleet Science Center.

We often think of metals as being these hard, tough, heavy, almost invincible things.  But in reality, there are a ton—no pun intended—of different varieties of metals. Some metals bend easily and other metals are stiff.  Some metals can withstand incredibly high amounts of heat before melting and other metals melt at incredibly low temperatures—like mercury which has a lower melting point than ice!  That means if you cooled down mercury and water together down to the point that the water turns to ice, the mercury would still be a liquid!

Bismuth  is a crystalline white metal that is still solid at room temperature, however, it doesn’t take much to melt it. Once molten, after the bismuth cools back down, it organizes its molecules into really interesting shapes. When matter organizes its molecules into a more specific pattern, it creates a crystal. The salt we put on our food organizes its molecules into teeny tiny cubes, although it’s a little harder to see these little cubes after you’ve eaten them. Though not entirely unique, contrary to popular belief, water can crystallize into the six-sided shapes we know as snowflakes.  

In my opinion, bismuth crystals are even more fascinating than the rest. I like to imagine a foreman in a tiny crystal factory telling his designer to make a new crystal: 

Foreman: Ok, make the bismuth crystal look like stairs. 

Designer: Stairs, got it. 

Foreman: But not just any stairs, make them go on four sides and then go down into the middle. 

Designer: But if all the stairs go down into the middle won’t they all meet and end up not going anywhere? 

Foreman: Fine, then make it stairs on four sides but also like a square spiral. 

Designer: Boss, you ok? 

Foreman: Oh also! Make it rainbow-colored. 

Designer: 

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The structure of a bismuth crystal is just so wild and the beautiful color that happens when it oxidizes is captivating. When metal oxidizes, it means that its outer layer has changed because of its exposure to the oxygen in the air around us. When iron oxidizes, it gets a red-orange colored layer we call rust. When bismuth oxidizes, however, you can see so many colors; like pink, purple, green, blue and yellow.  Want to see it happen? Check out our video below where we make bismuth crystals in Studio X!