What is responsible for the properties minerals have?
All minerals are crystalline by nature, but there are still many differences between them. The chemical makeup and atomic structure of a mineral determine what properties that mineral will possess. The traits primarily used to identify minerals are color, streak, luster, density, hardness, fracture, cleavage, tenacity and crystal habit. The combination of these traits work together to help differentiate one mineral from an other and prevent misidentification. For example, streak (the color of a mineral when it is ground into a powder) can often be more accurate than overall color because small amounts of impurities may discolor a chunk of the mineral, but will not show as strongly in the streak. Each crystal structure also has different ways they are most likely to grow (crystal habit) and ways that the structures are most likely to break or fracture (cleavage and fracture). The internal structure, driven by the chemical composition of the mineral, decides all of these properties.