What are the 2 hardest substances on earth?

For many years, diamond was known as the "world's hardest material" before losing that place to slightly harder man-made materials. Two new substances, which occur naturally but are rare, have now taken the spotlight. Wurtzite boron nitride is similar to diamond, but is made up of different atoms and is 18% harder. Mineral lonsdaleite, which shares the same carbon atoms as diamond just arranged differently, is a whopping 58% harder.
Updated on Saturday, October 22 2011 at 01:32AM EDT
Source: www.newscientist.com/...