Fractures are very common in most rocks and minerals, as they are caused by the tremendous pressure that can be present due to the weight of the overlaying rocks, movement of nearby rocks, etc. Hardness is a property that is commonly used to describe how resistant a mineral is to scratching. There is a well established hardness scale for minerals known as the Mohs' hardness scale- with 1 being assigned to the softest minerals and 10 for the hardest. The very softest can be scratched by a fingernail, harder minerals by a nail and knife. Luster refers to the appearance of light that is reflected from the surface of a mineral.
Some minerals look 'dull' in luster, and some look 'shiny', for example.
Permeability is the ability of a rock or mineral to transmit fluids. It is closely related to porosity, or how much open space is in-between particles of a rock. However, for a rock to be permeable, the pore spaces must be connected so that fluids can move through the rock. Porosity is the volume of open spaces in a rock. On the other hand, sandstone, which is formed by individual sand grains compacting together, generally has a high degree of porosity.