Wurtzite boron nitrides are forever!

http://www.sciam.com/blog…says-2009-02-19

In addition to being the traditional token of marital intent, the diamond has long provided the—ahem—gold standard for super-hard materials. But physicists at Shanghai Jiao Tong University and at the University of Nevada, Las Vegas, say that two lesser-known materials, wurtzite boron nitride and lonsdaleite, are even harder.

scientific american

I rather like the fact that this research was done in Las Vegas.