Remember minerals differ from one another because each has a specific chemical composition and a unique three-dimensional arrangement of atoms within its structure. These differences result in a variety of physical properties, including the minerals' appearance, how they break, how well they resist being scratched, even how they smell, taste, and feel. Not all of these properties are equally useful. Some aspects of human features change markedly with time, while others, like eye color or shape of head, do not. The problem is the same with minerals.
Some properties never change.
These are the most useful for identifying a mineral and are called diagnostic properties. You should be able to decide which of the following properties are truly diagnostic properties, and which are less useful. Click on each of the physical properties below to learn what they are and how to use them to identify minerals. Now you are ready to enter the world of minerals. Let's try to identify some common minerals.