In chemistry, mineralogy and materials science, a crystal is a solid in which the constituent atoms, molecules or ions are packed in a regularly ordered, repeating pattern extending in all three spatial dimensions. The word crystal is derived from the ancient Greek word krustallos, which had the same meaning, but according to the ancient understanding of crystal. At root, it means anything congealed by freezing, such as ice. The word once referred particularly to quartz, or “rock crystal”.
Most metals encountered in everyday life are polycrystals. Crystals are often symmetrically grown to form crystal twins. There are numerous applications of crystals, including jewelry and home décor figures. In my home I keep a collection of exquisite quartz crystal points on the mantel.
