Geology Online Chapters
Common crystal / mineral crystal forms - Minerals are the natural material that every inorganic material on planet Earth is composed of. Individual minerals must have the same chemical composition. The structure that results from such arrangement is called a crystal and is the external expression of the orderly arrangement of atoms and molecules.
Crystal Structure and Crystal Systems
Crystal Structure and Crystal System - Reflection, rotation, inversion, and rotoinversion are all point symmetry operations.