Hardest substance in the world is wurtzite boron nitride when crashed into itself
 Diamond is the hardest naturally occurring substance found on Earth. But it is not the hardest substance. Wurtzite boron nitride (synthetic) and lonsdaleite (which comes from meteorites) are both harder.
- Marcy Seavey (age 39)
Waterloo, Iowa USA
You are only the person to give the answer because I have kept the question yesterday
The Brainliest Answer!
I think it is diamond. It can only be broken when cut by itself :)
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