The 4 Major characteristics of a mineral are:
1. It is formed by natural processes, not man-made.
2. It is inorganic, it's not alive, it will never be.
3. It is a crystalline solid, a definite volume and shape with a repeating structure.
4. It can be an element or compound with a definite chemical composition, made the same each time with and orderly arrangement of atoms.
Also another answer might be:
1.Texture
2. Hardness
3.Luster or shine
4.Color/Streak
Hope this helps.