Round 2 Match 2
It's time to pick your gem!
Corundum is famous by its other names, ruby and sapphire. This hexagonal crystal nearly tops the scale for hardness at Mohs 9, and may fluoresce under UV light. Crystals show off their shine when cut and polished, with some demonstrating asterism, 6- or 12-pointed stars of reflected or refracted light. Corundum was first synthetically grown in 1837.
Wavellite is a more unusual gemstone, a soft translucent green mineral. The crystals form as bubbly crusts, precipitating in watery cracks, and even as stalactites. Its radiating spheres can form fascinating starbursts or cats-eyes when the glittery clusters are broken open. It, too, can fluoresce under UV light. The intensity of green is related to the trace vanadium within the crystals, varying from emerald or lime green all the way to white or even colourless.
Read campaign highlights from the Round 1 matches won by Corundum and Wavellite.
Corundum from Sri Lanka and Wavellite from Arkansas. Image credit: Smithsonian Institute
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