Hardness is measured on the Mohs scale. A hard mineral is rigid, resistant to pressure and is not easily scratched. Determining the hardness (or relative hardness) of a mineral in hand specimen can aid your identification of the mineral.

The three dimensional shape of a crystal. The crystal structure of a mineral influences the characteristic habit(s) which it displays. For example, biotite mica tends to display a platy or tabular habit because its crystal lattice is made up of sheets.

Rapidly cooled magmas are largely made-up of many tiny crystals. These make up the groundmass.

This texture refers to an igneous or metamorphic rock which consists entirely of interlocking, roughly equant grains, large enough to be seen with naked eye.