The scientific definition of a "crystal" is based on the microscopic arrangement of atoms inside it, called the crystal structure. A crystal is a solid where the atoms form a periodic arrangement. (Quasicrystals are an exception, see below). Not all solids are crystals.

Negative Photoconductivity in Ultranarrow-Gap Semiconductors Microstructures of Fe-16wt%S-2wt%Si in Partial and Complete Melt Regions at High Pressures: Implications for Dynamics in Small Planetary Cores Liquid Crystal Dimers Based on Seven-Membered Bridged Stilbene Exhibiting Twist-Bend Nematic Phases

The most interesting crystal structures are those of elements that are neither metallic, covalent, nor diatomic. Although boron (B) and sulfur (S) have several different crystal structures, each has one arrangement in which it is usually found.

A crystal is a solid material in which atoms, ions, or molecules are arranged in a highly ordered and repeating three-dimensional pattern, known as a crystal lattice.

For gemologists and mineralogists, the scientific definition of a crystal goes right to the atomic level. A crystal is a solid whose atoms are arranged in a "highly ordered" repeating pattern.

Check out our extensive guide to crystal meanings & stone properties with beautiful pictures. Find the right crystal or stone for you by learning their healing powers.

There are thousands of types of crystals. Below is an alphabetical list of crystals along with pictures and a short description of each crystal type.

The Crystal Encyclopedia is the definitive guide to crystals, stones, and minerals. Find everything you've ever wanted to know about crystals!