What is toughness in mineralogy ?

Toughness : definition

Toughness is the resistance offered by a mineral to fracture, under the effect of a hammer blow or between the jaws of a crusher. This property depends on the chemical bonds within a mineral ; it cannot be measured directly and is expressed in qualitative terms : brittle, flexible, malleable, sectile or elastic.

It is defined on independent crystals, the tenacity of a crystal usually being different from that of an aggregate, the latter involving the entanglement of the crystals between them.

Toughness is a different parameter from scratch resistance, expressed by hardness.