Diamond: This is the most common answer, and for good reason. It's incredibly hard on the Mohs scale (the most widely used measure), scoring a perfect 10. Its hardness stems from its incredibly strong carbon-carbon bonds.
Lonsdaleite: Also known as hexagonal diamond, this rare form of carbon is even harder than diamond in some tests, but it's extremely rare and not often found in large enough quantities to be useful.
Wurtzite Boron Nitride: This material, which is structurally similar to diamond but with boron and nitrogen instead of carbon, is theorized to be even harder than diamond. However, it is also extremely rare and difficult to synthesize.
Fullerite: This material is made of buckminsterfullerene molecules, which are carbon molecules in a spherical shape. While not as hard as diamond, fullerite is remarkably strong and exhibits excellent resistance to compression and abrasion.
Other materials: Depending on the specific application, other materials like *Carbyne* or even certain types of *wood* could be considered incredibly hard for their specific use.
Ultimately, the "hardest natural material" depends on how you define hardness and what properties are most important for your application.
