<h3>Definition of Crystal:</h3><p>A substance in which the constituent <a href="https://www.thoughtco.com/definition-of-atom-and-examples-604373" data-component="link" data-source="inlineLink" data-type="internalLink" data-ordinal="1">atoms</a>, <a href="https://www.thoughtco.com/definition-of-molecule-605888" data-component="link" data-source="inlineLink" data-type="internalLink" data-ordinal="2">molecules</a>, or <a href="https://www.thoughtco.com/definition-of-ion-604535" data-component="link" data-source="inlineLink" data-type="internalLink" data-ordinal="3">ions</a> are packed in a regularly ordered, repeating three-dimensional pattern. Most crystals are <a href="https://www.thoughtco.com/definition-of-solid-604648" data-component="link" data-source="inlineLink" data-type="internalLink" data-ordinal="4">solids</a>.</p><h3>Examples of Crystals:</h3><p>quartz, <a href="https://www.thoughtco.com/sugar-crystals-and-rock-candy-pictures-4123170" data-component="link" data-source="inlineLink" data-type="internalLink" data-ordinal="5">rock candy</a>, <a href="https://www.thoughtco.com/crystal-photo-gallery-4064886" data-component="link" data-source="inlineLink" data-type="internalLink" data-ordinal="6">halite</a><br/><br/><strong><a href="https://www.thoughtco.com/chemistry-terms-starting-with-letter-a-604486" data-component="link" data-source="inlineLink" data-type="internalLink" data-ordinal="7">Return to the Chemistry Glossary Index</a></strong></p>