How do crystals form?
Crystals are solids with long-range order among atoms, ions, or molecules. They may form from solutions, cooling melts, or deposition from gas. A regular external shape alone does not prove crystallinity; internal structure must be examined.
Nucleation and growth
Crystallization often begins with a small stable nucleus. Building units then attach to appropriate surfaces. Temperature, supersaturation, impurities, and cooling rate influence nucleation and growth. Many nuclei may produce small grains, while fewer nuclei can allow larger crystals. The same chemical composition can support different structures under different conditions, as illustrated by diamond and graphite.
Properties and investigation
Crystal structure affects hardness, electrical behavior, and optical properties. X-ray diffraction reveals information about atomic spacing. Amorphous solids such as glass lack the same long-range periodic order, but are not therefore ordinary flowing liquids. Real crystals contain vacancies, impurities, and grain boundaries that affect behavior. Their scientific significance lies in measurable structure and properties, not claims about changing health or luck.