Final answer:
Hardness describes a mineral's resistance to being scratched, which is determined using the Mohs scale of mineral hardness. The scale ranks minerals from 1 to 10, higher numbers indicating harder minerals. The hardness relates to the tight bonds between ions in the mineral's structure.
Step-by-step explanation:
Hardness in the context of minerals refers to a mineral's resistance to being scratched. It is measured using the Mohs scale of mineral hardness, which ranges from 1 to 10, with higher numbers indicating a harder mineral. This scale is based on the relative ability of one mineral to scratch another and is considered a qualitative measure; for example, a mineral with a Mohs hardness of 10 is not 10 times harder than a mineral with a Mohs hardness of 1.
The hardness of a mineral is influenced by how tightly the ions are held together in its structure, which, in turn, is related to the lattice energy of the material. For instance, magnesium oxide (MgO) is harder than sodium fluoride (NaF) because it has a higher lattice energy and, hence, its ions are held more tightly.