Explain why each mineral has its own properties, different from every other mineral.

This is in the wrong section, but each mineral are different because they are made up of atoms and atoms are different from each other. Their differences come from the variability of atoms. 

No atom is alike one another because they have different numbers (protons). Hydrogen is 1, Helium is 2, etc. etc. you get it. Every atom has a different chemical composition, therefore altering a mineral's physical appearance, and other characteristics.