Final answer:
Covalent bonds result in the highest hardness in minerals, exemplified by the hardness of diamond, which is made of a network of covalently bonded carbon atoms 3.covalent.
Step-by-step explanation:
The bond type that leads to the highest hardness in minerals is the covalent bond.
Unlike ionic bonds or metallic bonds, which involve the transfer or pooling of electrons respectively, a covalent bond involves the sharing of electrons between atoms.
This sharing of electrons leads to the formation of strong, directional bonds that hold the atoms in a fixed position, creating a rigid and hard structure. For example, diamond, which is the hardest known natural substance, consists of a three-dimensional network of covalently bonded carbon atoms.
On the other hand, van der Waals interactions are far weaker than covalent bonds, as they are based on temporary dipoles that do not create a fixed, rigid structure necessary for high hardness.