Here's why:
* Crystalline boron's hardness: It has a Mohs hardness of 9.5, making it one of the hardest elements.
* Other contenders for hardest material: Materials like diamond, wurtzite boron nitride (w-BN), and lonsdaleite (hexagonal diamond) have higher hardness values and are considered harder than crystalline boron.
* Hardness measurement: It's important to note that hardness can be measured in different ways, and there's no single universally accepted standard.
Therefore, while crystalline boron is incredibly hard, it's not the hardest material known to science.
