Salt, Diamonds and DNA: 5 Surprising Facts About Crystals

When you think crystals, you probably think of flashy rocks behind glass in a natural history museum, but crystal forms are incredibly diverse and can be found in your kitchen and even inside your very own body. 2014 marks the international year of crystallography, so in its honor, we’ve put together a list of five crystal facts, and you’d better believe they’re going to rock your world. But first, let’s run through exactly what a crystal is? In short, a crystal is a uniformed material with a really consistent internal molecular structure. Deep down inside a crystal you’ll see a very unique arrangement of molecules and atoms in a structure called crystal lattice. When you think lattice, think cage. Salt started the science. Let’s start with a very famous crystal: salt. What makes salt stand out? It started the crystal craze. Father and son duo Henry and Lawrence Bragg wanted to know how salt formed. In 1913, they used x-rays to figure out what crystal structures look like. For this, they won the 1915 Nobel Prize and kicked off a completely new field of science. Hats off to you team Bragg! But why no Nobel Prize for whoever discovered putting salt on French fries? There is a crystal even stronger than diamonds. Diamonds are tough, but there’s one crystal that’s even tougher. Wurtzite Boron Nitride is shaped very similar to diamond, except instead of carbon atoms, it’s made up of boron and nitrogen. What makes it such a strong crystal is that when great stress is applied to it, the molecular bonds that keep it together have the ability to reorient themselves to relieve tension. While diamonds also do this, a Boron Nitride crystal ends up being about 80% stronger. DNA is a crystal structure. If you paid attention in biology class you learned that Watson and Crick discovered the structure of DNA in 1953. It even won them a Nobel Prize. But it might not have happened without the help of crystallographer Rosalind Franklin. Franklin’s work in x-ray diffraction helped prove their theoretical models, leading to one of the most important scientific discoveries of the 20th century. Earth’s largest crystals are also found in drywall The crystal cave of Mexico, deep below the Naica Mountain in the Chihuahuan Desert, is filled with some of the largest known crystal structures on Earth. Primarily made of gypsum – the same stuff used to make drywall – these crystals range up to 36 feet tall and can weigh up to 55 tons. The most expensive diamond on Earth is pink. The pink star diamond is the most expensive diamond on the planet, per carat. But before we get to the astronomical numbers, you might be wondering what exactly a carat is. Well it’s simple. A carat is a unit of measurement for precious stones that equals 200mg. So, one carat of the Pink Star Diamond is worth $1,395,761, or $6,972.81 cents per milligram of diamond. This shiny little rock here, yeah, it’s worth over $83,000,000, and it’s 59.6 carat size. Crystallography has brought on an incredible scope of discoveries over the past centuries, so make sure to check down in the video description for a list of C&EN’s favorite crystal structures. If you’ve got any chemistry questions, leave it in the comments or find us on Facebook and Twitter at acsreactions.


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