Crystal | Definition, Types, Structure, & Facts

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class="md-content"> <div class="md-article-container template-desktop infinite-pagination"> <div class="infinite-scroll-container article last"> <article class="article-content container-lg qa-content px-0 pt-0 pb-40 py-lg-20 content md-expanded" data-topic-id="145105"> <div class="grid gx-0"> <div class="col-auto"> <div class="topic-left-rail md-article-drawer position-relative d-flex border-right-sm border-left-sm open"> <div class="drawer d-flex flex-column open"> <div class="left-rail-section-content"> <div class="topic-left-rail-header text-truncate bg-gray-50 position-relative text-right d-flex align-items-center"> <div class="tlr-title px-20 py-15 text-left"> <em class="material-icons text-gray-400 d-lg-none" data-icon="toc"></em> <a class="font-serif font-weight-bold text-black link-blue" href="https://www.britannica.com/science/crystal">crystal</a> </div> <button aria-label="Close" class="js-sections-close-button btn-link btn-sm btn d-lg-none position-absolute top-0 p-10 right-0" > <em class="material-icons font-26" data-icon="close"></em> </button> </div> <div class="section-content pl-10 pr-20 pl-sm-50 pr-sm-60 pl-lg-5 pr-lg-10 pt-10 pt-lg-0 bg-gray-50 clear-catfish-ad"> <div class="toc mb-20"> <div class="font-serif font-14 font-weight-bold mx-15 mb-15 mt-20"> Table of Contents </div> <ul class="list-unstyled my-0" data-level="h1"><li data-target="#ref1"><div class="pl-25"><a class="link-gray-900 w-100" href="/science/crystal">Introduction</a></div><div class="ml-40 toc-drawer sub-toc-drawer"></div></li><li data-target="#ref51802"><div class="d-flex align-items-center"><button class="h1-link-drawer-button btn btn-xs btn-circle d-flex rounded" type="button" aria-label="Toggle Heading"><em class="material-icons font-18" data-icon="keyboard_arrow_right"></em></button><a class="w-100 link-gray-900" href="/science/crystal#ref51802">Classification</a></div><div class="ml-40 toc-drawer sub-toc-drawer"><ul class="list-unstyled" data-level="h2"><li data-target="#ref51803"><a class="w-100 link-gray-900" href="/science/crystal#ref51803">Basic units of solids</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref51804"><a class="w-100 link-gray-900" href="/science/crystal#ref51804">Long- and short-range order</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref51805"><a class="w-100 link-gray-900" href="/science/crystal#ref51805">Categories of crystals</a></li></ul></div></li><li data-target="#ref51806"><div class="d-flex align-items-center"><button class="h1-link-drawer-button btn btn-xs btn-circle d-flex rounded" type="button" aria-label="Toggle Heading"><em class="material-icons font-18" data-icon="keyboard_arrow_right"></em></button><a class="w-100 link-gray-900" href="/science/crystal/Structure">Structure</a></div><div class="ml-40 toc-drawer sub-toc-drawer"><ul class="list-unstyled" data-level="h2"><li data-target="#ref51807"><a class="w-100 link-gray-900" href="/science/crystal/Structure#ref51807">The unit cell</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref51808"><a class="w-100 link-gray-900" href="/science/crystal/Structure#ref51808">Structures of metals</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref51809"><a class="w-100 link-gray-900" href="/science/crystal/Structure#ref51809">Structures of nonmetallic elements</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref51810"><a class="w-100 link-gray-900" href="/science/crystal/Structure#ref51810">Structures of binary crystals</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref51811"><a class="w-100 link-gray-900" href="/science/crystal/Alloys">Alloys</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref51812"><a class="w-100 link-gray-900" href="/science/crystal/Alloys#ref51812">Crystal defects</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref51813"><a class="w-100 link-gray-900" href="/science/crystal/Alloys#ref51813">Determination of crystal structures</a></li></ul></div></li><li data-target="#ref51814"><div class="d-flex align-items-center"><button class="h1-link-drawer-button btn btn-xs btn-circle d-flex rounded" type="button" aria-label="Toggle Heading"><em class="material-icons font-18" data-icon="keyboard_arrow_right"></em></button><a class="w-100 link-gray-900" href="/science/crystal/Types-of-bonds">Types of bonds</a></div><div class="ml-40 toc-drawer sub-toc-drawer"><ul class="list-unstyled" data-level="h2"><li data-target="#ref51815"><a class="w-100 link-gray-900" href="/science/crystal/Types-of-bonds#ref51815">Ionic bonds</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref51816"><a class="w-100 link-gray-900" href="/science/crystal/Types-of-bonds#ref51816">Covalent bonds</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref51817"><a class="w-100 link-gray-900" href="/science/crystal/Types-of-bonds#ref51817">Metallic bonds</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref51818"><a class="w-100 link-gray-900" href="/science/crystal/Molecular-binding">Molecular binding</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref51819"><a class="w-100 link-gray-900" href="/science/crystal/Molecular-binding#ref51819">Hydrogen bonding</a></li></ul></div></li><li data-target="#ref51820"><div class="d-flex align-items-center"><button class="h1-link-drawer-button btn btn-xs btn-circle d-flex rounded" type="button" aria-label="Toggle Heading"><em class="material-icons font-18" data-icon="keyboard_arrow_right"></em></button><a class="w-100 link-gray-900" href="/science/crystal/Molecular-binding#ref51820">Crystal growth</a></div><div class="ml-40 toc-drawer sub-toc-drawer"><ul class="list-unstyled" data-level="h2"><li data-target="#ref51821"><a class="w-100 link-gray-900" href="/science/crystal/Molecular-binding#ref51821">Vapour growth</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref51822"><a class="w-100 link-gray-900" href="/science/crystal/Molecular-binding#ref51822">Growth from solution</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref51823"><a class="w-100 link-gray-900" href="/science/crystal/Growth-from-the-melt">Growth from the melt</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref51824"><a class="w-100 link-gray-900" href="/science/crystal/Growth-from-the-melt#ref51824">Dendritic growth</a></li></ul></div></li><li data-target="#ref51825"><div class="d-flex align-items-center"><button class="h1-link-drawer-button btn btn-xs btn-circle d-flex rounded" type="button" aria-label="Toggle Heading"><em class="material-icons font-18" data-icon="keyboard_arrow_right"></em></button><a class="w-100 link-gray-900" href="/science/crystal/Electric-properties">Electric properties</a></div><div class="ml-40 toc-drawer sub-toc-drawer"><ul class="list-unstyled" data-level="h2"><li data-target="#ref51826"><a class="w-100 link-gray-900" href="/science/crystal/Electric-properties#ref51826">Resistivity</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref51827"><a class="w-100 link-gray-900" href="/science/crystal/Electric-properties#ref51827">Conduction through ion hopping</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref51828"><a class="w-100 link-gray-900" href="/science/crystal/Electric-properties#ref51828">Conduction electrons</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref51829"><a class="w-100 link-gray-900" href="/science/crystal/Electric-properties#ref51829">Electrical insulators</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref51830"><a class="w-100 link-gray-900" href="/science/crystal/Conductivity-of-metals">Conductivity of metals</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref51831"><a class="w-100 link-gray-900" href="/science/crystal/Conductivity-of-metals#ref51831">Conducting properties of semiconductors</a></li></ul></div></li><li data-target="#ref51832"><div class="d-flex align-items-center"><button class="h1-link-drawer-button btn btn-xs btn-circle d-flex rounded" type="button" aria-label="Toggle Heading"><em class="material-icons font-18" data-icon="keyboard_arrow_right"></em></button><a class="w-100 link-gray-900" href="/science/crystal/Magnetism">Magnetism</a></div><div class="ml-40 toc-drawer sub-toc-drawer"><ul class="list-unstyled" data-level="h2"><li data-target="#ref51833"><a class="w-100 link-gray-900" href="/science/crystal/Magnetism#ref51833">Explanation of magnetism</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref51834"><a class="w-100 link-gray-900" href="/science/crystal/Magnetism#ref51834">Ferromagnetic materials</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref51835"><a class="w-100 link-gray-900" href="/science/crystal/Magnetism#ref51835">Antiferromagnetic materials</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref51836"><a class="w-100 link-gray-900" href="/science/crystal/Ferrimagnetic-materials">Ferrimagnetic materials</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref51837"><a class="w-100 link-gray-900" href="/science/crystal/Ferrimagnetic-materials#ref51837">The Kondo effect</a></li></ul></div></li></ul> <a class="toc-extra-link link-gray-900" href="https://www.britannica.com/science/crystal/additional-info">References & Edit History</a> <a class="toc-extra-link link-gray-900" href="/facts/crystal">Quick Facts & Related Topics</a> </div> <div class="tlr-media-slider pb-10 mb-30"> <a class="section-header link-gray-900 font-serif font-14 font-weight-bold mb-10 mx-10" href="https://www.britannica.com/science/crystal/images-videos">Images & Videos</a> <div class="slider js-slider position-relative d-inline-flex align-items-center mw-100 "> <div class="slider-container js-slider-container overflow-hidden d-flex overflow-hidden text-nowrap ml-15"> <a href="/video/Minerals-motifs-one-crystal-systems/148013" data-href="/media/1/145105/148013" class="media-overlay-link d-inline-block mr-5"> <div class="position-relative --aspect-ratio: 16/9"> <img loading="lazy" src="https://cdn.britannica.com/66/143166-138-587B4B3D/Minerals-motifs-one-crystal-systems.jpg?w=400&h=225&c=crop" alt="Learn how the shape of the crystals determine the different minerals into families" class="col-100" /> <div class="btn btn-sm btn-white btn-circle position-absolute shadow" style="top: 50%; left:50%; transform: translate(-50%, -50%)"> <em class="material-icons font-14" data-icon="play_arrow" > </em> </div> </div> </a> <a href="https://cdn.britannica.com/67/2367-004-4729A4A0/Unit-cells-lattices.jpg" data-href="/media/1/145105/2226" class="media-overlay-link d-inline-block mr-5"> <img loading="lazy" src="https://cdn.britannica.com/67/2367-004-4729A4A0/Unit-cells-lattices.jpg" alt="Figure 1: Unit cells for face-centred and body-centred cubic lattices." height="50" /> </a> <a href="https://cdn.britannica.com/68/2368-004-FDA5B17F/spheres-arrangements.jpg" data-href="/media/1/145105/2227" class="media-overlay-link d-inline-block mr-5"> <img loading="lazy" src="https://cdn.britannica.com/68/2368-004-FDA5B17F/spheres-arrangements.jpg" alt="Figure 2: Stacking of spheres in closest-packed arrangements." height="50" /> </a> <a href="https://cdn.britannica.com/70/2370-004-AFDB2603/Crystal-structures-number-types-ions-sodium-chloride.jpg" data-href="/media/1/145105/2231" class="media-overlay-link d-inline-block mr-5"> <img loading="lazy" src="https://cdn.britannica.com/70/2370-004-AFDB2603/Crystal-structures-number-types-ions-sodium-chloride.jpg" alt="Figure 3: Crystal structures. There is an equal number of the two types of ions in the unit cell of the (A) cesium chloride, (B) sodium chloride, and (D) zinc blende arrangements. The diamond arrangement is shown in (C). If both atoms are identical in (A), the structure is body-centred cubic." height="50" /> </a> <a href="https://cdn.britannica.com/71/2371-004-75002E54/arrangement-boron-molecules.jpg" data-href="/media/1/145105/2229" class="media-overlay-link d-inline-block mr-5"> <img loading="lazy" src="https://cdn.britannica.com/71/2371-004-75002E54/arrangement-boron-molecules.jpg" alt="Figure 4: The icosahedral arrangement of boron molecules." height="50" /> </a> <a href="https://cdn.britannica.com/72/2372-004-62AE8444/lattice-defect-edge-dislocation-row-Region-atoms.jpg" data-href="/media/1/145105/2240" class="media-overlay-link d-inline-block mr-5"> <img loading="lazy" src="https://cdn.britannica.com/72/2372-004-62AE8444/lattice-defect-edge-dislocation-row-Region-atoms.jpg" alt="Figure 5: Crystalline lattice defect. An edge dislocation occurs when there is a missing row of atoms as shown in region b. Region a is strained." height="50" /> </a> <a href="https://cdn.britannica.com/74/2374-004-A7A6AE83/Incident-rays-angle-difference-planes-atoms-Rays.jpg" data-href="/media/1/145105/2235" class="media-overlay-link d-inline-block mr-5"> <img loading="lazy" src="https://cdn.britannica.com/74/2374-004-A7A6AE83/Incident-rays-angle-difference-planes-atoms-Rays.jpg" alt="Figure 6: Incident rays (1 and 2) at angle θ on the planes of atoms in a crystal. Rays reinforce if their difference in path length (AB + BC) is an integer times the wavelength of the X ray." height="50" /> </a> <a href="https://cdn.britannica.com/72/105672-050-32A376C1/types-bonding-crystals.jpg" data-href="/media/1/145105/148656" class="media-overlay-link d-inline-block mr-5"> <img loading="lazy" src="https://cdn.britannica.com/72/105672-004-2E90DA7F/types-bonding-crystals.jpg" alt="crystal bonding" height="50" /> </a> <a href="https://cdn.britannica.com/75/2375-004-3949AB91/Crystal-method-Czochralski-view-apparatus.jpg" data-href="/media/1/145105/2228" class="media-overlay-link d-inline-block mr-5"> <img loading="lazy" src="https://cdn.britannica.com/75/2375-004-3949AB91/Crystal-method-Czochralski-view-apparatus.jpg" alt="Figure 7: Crystal pulling using the Czochralski method. A schematic view of a modern apparatus." height="50" /> </a> <a href="/video/snowflakes/208085" data-href="/media/1/145105/208085" class="media-overlay-link d-inline-block mr-5"> <div class="position-relative --aspect-ratio: 16/9"> <img loading="lazy" src="https://cdn.britannica.com/19/188819-138-D26BD932/snowflakes.jpg?w=400&h=225&c=crop" alt="How do snowflakes form?" class="col-100" /> <div class="btn btn-sm btn-white btn-circle position-absolute shadow" style="top: 50%; left:50%; transform: translate(-50%, -50%)"> <em class="material-icons font-14" data-icon="play_arrow" > </em> </div> </div> </a> </div> <button disabled class="prev-button js-prev-button position-absolute btn btn-circle shadow btn-blue " aria-label="Previous"> <span class="material-icons md-24" data-icon="keyboard_arrow_left"></span> </button> <button disabled class="next-button js-next-button position-absolute btn btn-circle shadow btn-blue " aria-label="Next"> <span class="material-icons md-24" data-icon="keyboard_arrow_right"></span> </button> </div> </div> <div class="mb-30 tlr-student-links"> <div class="text-gray-900 p-5 font-serif font-14 font-weight-bold mx-10 mb-10"> For Students </div> <div class="imagelink-with-image-on-the-side card card-horizontal tlr-img-with-side-link ml-15 link-gray-900 mb-10" > <div class="position-relative card-media" style="flex: 0;"> <a class="ilf-image position-relative" href="/summary/crystal"> <img loading="lazy" src="https://cdn.britannica.com/74/119074-050-A55D2829/halite-crystals.jpg?w=200&h=200&c=crop" alt="halite crystals" width="200" height="200" /> </a> </div> <div class="card-body ilf-content"> <a class="font-weight-semi-bold d-block mb-5 font-16 ilf-title" href="/summary/crystal" >crystal summary</a> </div> </div> </div> <div class="mb-30 tlr-discover"> <div class="text-gray-900 p-5 font-serif font-14 font-weight-bold mx-10 mb-10"> Discover </div> <div class="imagelink-with-image-on-the-side card card-horizontal tlr-img-with-side-link ml-15 link-gray-900 mb-10" > <div class="position-relative card-media" style="flex: 0;"> <a class="ilf-image position-relative" href="/list/americas-5-most-notorious-cold-cases-including-one-you-may-have-thought-was-already-solved"> <img loading="lazy" src="https://cdn.britannica.com/71/196471-131-8FEA8DDD/Daily-Police-Bulletin-Elizabeth-Short-Black-Dahlia-January-1947.jpg?w=200&h=200&c=crop" alt="Los Angeles Police Department wanted flyer on Elizabeth Short, aka the "Black Dahlia," who was brutally murdered in January 1947. 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Let us know if you have suggestions to improve this article (requires login). </div> <div class="type-menu"> <label for="feedback-type" class="label mb-10">Feedback Type</label> <select id="feedback-type" class="form-select mb-30" name="feedbackTypeId" required> <option value="" selected="selected">Select a type (Required)</option> <option value="1">Factual Correction</option> <option value="2">Spelling/Grammar Correction</option> <option value="3">Link Correction</option> <option value="4">Additional Information</option> <option value="5">Other</option> </select> </div> <label for="feedback" class="label mb-10">Your Feedback</label> <textarea id="feedback" class="form-control mb-30" name="feedback" maxlength="3000" rows="7" required></textarea> <button class="btn btn-blue" type="submit">Submit Feedback</button> </form> <div class="success-messaging d-none mt-30"> <div class="title">Thank you for your feedback</div> <p>Our editors will review what you’ve submitted and determine whether to revise the article.</p> </div> </div> </div> <div class="md-websites-modal size-lg d-none"> <div class="md-modal-body"> <div class="h2 font-serif pb-15 border-bottom font-weight-bold"> External Websites </div> <div class="pb-20"> <ul class="list-unstyled mt-20 lh-lg"> <li><a class="external" href="https://core.ac.uk/download/pdf/81953859.pdf" target="_blank" rel="noopener ">CORE - Generalized Symmetry in Crystal Physics</a></li> <li><a class="external" href="https://unlcms.unl.edu/cas/physics/tsymbal/teaching/SSP-927/Section%2001_Crystal%20Structure.pdf" target="_blank" rel="noopener ">University of Nebraska–Lincoln - Crystal Structure</a></li> <li><a class="external" href="https://nature.berkeley.edu/classes/eps2/wisc/oLect4.html" target="_blank" rel="noopener ">University of California Berkeley - College of Natural Resources - What is a Crystal?</a></li> <li><a class="external" href="https://chem.libretexts.org/Bookshelves/Analytical_Chemistry/Physical_Methods_in_Chemistry_and_Nano_Science_(Barron)/07%3A_Molecular_and_Solid_State_Structure/7.01%3A_Crystal_Structure" target="_blank" rel="noopener ">Chemistry LibreTexts - Crystal Structure</a></li> <li><a class="external" href="https://www.livescience.com/40347-crystal-healing.html" target="_blank" rel="noopener ">Live Science - Crystal healing: Stone-cold facts about gemstone treatments</a></li> <li><a class="external" href="https://www.ucl.ac.uk/~ucapikr/Solid_State_Physics/Section%201.pdf" target="_blank" rel="noopener ">London's Global University - Crystal Structure</a></li> <li><a class="external" href="https://www.svce.ac.in/wp-content/uploads/2021/01/Unit-1-Crystal-Physics-notes.pdf" target="_blank" rel="noopener ">Sri Venkateswara College Of Engineering - Crystal Physics</a></li> </ul> </div> <div class="md-websites-ebk-title">Britannica Websites</div> <div class="md-websites-ebk-subtitle">Articles from Britannica Encyclopedias for elementary and high school students.</div> <ul class="list-unstyled bps-topic-web-sites lh-lg"> <li><a class="external" href="https://kids.britannica.com/kids/article/crystal/399416" target="_blank" rel="noopener">crystal - Children's Encyclopedia (Ages 8-11)</a></li> <li><a class="external" href="https://kids.britannica.com/students/article/crystals/273872" target="_blank" rel="noopener">crystals - Student Encyclopedia (Ages 11 and up)</a></li> </ul> </div> </div> </div> </div> <div class="toc-header-marker"></div> <button class="ai-ask-button btn border-2 js-header-ai-ask-button d-none btn-sm btn-outline-red-400 border-red-400 mr-0 mr-lg-10 ml-5 ml-sm-10 ml-lg-0 p-10"> Ask the Chatbot a Question </button> <div class="caption alternate-titles">Also known as: crystal structure, crystalline solid</div> <div class="md-byline module-spacing "> <div class="font-serif font-12"> <span class="written-by text-gray-700"> Written by </span> <div class="editor-popover popover p-0"> <a class="d-block p-20 gtm-byline font-12 byline-contributor" href="/contributor/Gerald-D-Mahan/4076" > <div class="editor-title font-16 font-weight-bold">Gerald D. Mahan</div> <div class="editor-description font-12 font-serif mt-5 clamp-description text-black">Distinguished Professor of Physics, Pennsylvania State University, State College, Pa. Distinguished Scientist, Solid State Division, Oak Ridge National Laboratory, Tennessee. Author of <i>Many-Particle...</i></div> </a> <div data-popper-arrow></div> </div> <span class="btn btn-link editor-link p-0 qa-byline-link gtm-byline font-12 byline-contributor text-decoration-underline"> Gerald D. Mahan</span></div> <div class="font-serif font-12 text-gray-700"> <span class="qa-fact-checked-by">Fact-checked by</span> <div class="editor-popover popover p-0"> <a class="d-block p-20 font-12" href="/editor/The-Editors-of-Encyclopaedia-Britannica/4419" > <div class="editor-title font-16 font-weight-bold">The Editors of Encyclopaedia Britannica</div> <div class="editor-description font-12 font-serif mt-5 text-black">Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree. They write new content and verify and edit content received from contributors.</div> </a> <div data-popper-arrow></div> </div> <span class="btn btn-link editor-link p-0 qa-byline-link font-12 "> The Editors of Encyclopaedia Britannica</span></div> <div class="last-updated font-12 font-serif"> <span class="text-gray-700"> Last Updated: <time datetime="2024-11-23T00:00:00CST" >Nov 23, 2024</time> •</span> <a class="byline-edit-history" href="https://www.britannica.com/science/crystal/additional-info#history" rel="nofollow">Article History</a> </div></div> </div> <button class="d-flex d-lg-none btn btn-outline-blue border rounded-sm shadow-sm mobile-toc-button gtm-mobile-toc-inline-button d-none d-sm-block js-sections-inline-button module-spacing btn d-lg-none"> <em class="material-icons mr-5 ml-n10 my-n5 md-icon" data-icon="toc"></em> Table of Contents </button> <div class="d-flex d-sm-none flex-row"> <button class="d-flex d-lg-none btn btn-outline-blue border rounded-sm shadow-sm mobile-toc-button gtm-mobile-toc-inline-button js-sections-inline-button module-spacing"> <em class="material-icons mr-5 ml-n10 my-n5 md-icon" data-icon="toc"></em> Table of Contents </button> <button class="ai-ask-button btn border-2 ai-ask-button btn border-2 module-spacing btn-sm js-inline-ai-ask-button btn-outline-red-400 border-red-400 p-10 ml-5"> Ask the Chatbot a Question </button> </div> <div class="js-qf-module qf-module px-40 px-sm-20 py-15 mx-auto module-spacing font-14 bg-gray-50 rounded"> <div class="facts-list mt-10"> <div class=""> <div class="js-fact mb-10 line-clamp clamp-3"> <dl> <dt>Key People: </dt> <dd><a href="/biography/Nicolaus-Steno" topicid="565278">Nicolaus Steno</a></dd> <dd><a href="/biography/Ralph-Walter-Graystone-Wyckoff" topicid="650165">Ralph Walter Graystone Wyckoff</a></dd> <dd><a href="/biography/Max-von-Laue" topicid="332240">Max von Laue</a></dd> <dd><a href="/biography/Georges-Friedel" topicid="220121">Georges Friedel</a></dd> <dd><a href="/biography/Torbern-Olof-Bergman" topicid="61835">Torbern Olof Bergman</a></dd> </dl> <button class="js-more-btn d-none btn btn-unstyled font-12 bg-gray-50" aria-label="Toggle more/less fact data"> <em class="js-content link-blue">(Show more)</em> </button> </div> </div> <div class=""> <div class="js-fact mb-10 line-clamp clamp-3"> <dl> <dt>Related Topics: </dt> <dd><a href="/science/liquid-crystal" topicid="343083">liquid crystal</a></dd> <dd><a href="/science/pleochroism" topicid="464649">pleochroism</a></dd> <dd><a href="/science/double-refraction" topicid="170003">double refraction</a></dd> <dd><a href="/science/symmetry-crystallography" topicid="577899">symmetry</a></dd> <dd><a href="/science/polymorphism-crystals" topicid="468806">polymorphism</a></dd> </dl> <button class="js-more-btn d-none btn btn-unstyled font-12 bg-gray-50" aria-label="Toggle more/less fact data"> <em class="js-content link-blue">(Show more)</em> </button> </div> </div> <div class=""> <div class="js-fact mb-10 line-clamp clamp-3"> <dl> <dt>On the Web: </dt> <dd><a href="https://core.ac.uk/download/pdf/81953859.pdf" target="_blank">CORE - Generalized Symmetry in Crystal Physics</a> (Nov. 23, 2024)</dd> </dl> <button class="js-more-btn d-none btn btn-unstyled font-12 bg-gray-50" aria-label="Toggle more/less fact data"> <em class="js-content link-blue">(Show more)</em> </button> </div> <div class="text-center"> <a class="btn btn-sm btn-link p-0" href="/facts/crystal"> See all related content </a> </div> </div> </div> </div><span class="marker before-article"></span><section data-level="1" id="ref1"><span class="marker PREMOD1 mod-inline"></span><div class="assemblies"><div class="w-100"><figure class="md-assembly m-0 mb-md-0 card card-borderless print-false" data-assembly-id="148013" data-asm-type="video"><div class="md-assembly-wrapper card-media " data-type="video" video-id="143166"><a data-id="143166" class="gtm-assembly-link d-flex justify-content-center" style="--aspect-ratio: 16/9" href="/video/Minerals-motifs-one-crystal-systems/-148013"><img src="https://cdn.britannica.com/66/143166-138-587B4B3D/Minerals-motifs-one-crystal-systems.jpg?w=800&h=450&c=crop" alt="Learn how the shape of the crystals determine the different minerals into families" loading="lazy"><script type="application/json"> { "sources": [ { "file" : "//content.jwplatform.com/manifests/DiApwtNm.m3u8" } ], "image": "https://cdn.britannica.com/66/143166-138-587B4B3D/Minerals-motifs-one-crystal-systems.jpg" ,"tracks": [ { "file" : "//assets-jpcust.jwpsrv.com/tracks/X9rRitA5", "label": "English" } ] ,"adfile": "//content.jwplatform.com/manifests/lSGEHav6.m3u8" } </script><div class="btn btn-xl btn-white btn-circle position-absolute shadow" style="top: 50%; transform: translateY(-50%)"><em class="material-icons" data-icon="play_arrow"></em></div></a></div><figcaption class="card-body"><div class="md-assembly-caption text-muted font-14 font-serif line-clamp"><span><span class="md-assembly-title font-weight-bold mr-5 d-inline font-sans-serif md-video-caption" video-control="143166">Learn how the shape of the crystals determine the different minerals into families</span><span>Minerals crystallize according to one of seven motifs, known as crystal systems.</span><button class="js-more-btn d-none btn btn-unstyled font-12 bg-white js-content" aria-label="Toggle more/less fact data"><span class="link-blue">(more)</span></button></span></div><a class="font-14 mt-10 d-inline-block" href="/science/crystal/images-videos">See all videos for this article</a></figcaption></figure></div></div><p class="topic-paragraph"><strong><span id="ref506245"></span>crystal</strong>, any solid material in which the component atoms are arranged in a definite pattern and whose <a href="https://www.britannica.com/science/surface-chemistry-and-physics" class="md-crosslink autoxref " data-show-preview="true">surface</a> regularity reflects its internal <a href="https://www.britannica.com/science/symmetry-crystallography" class="md-crosslink autoxref " data-show-preview="true">symmetry</a>.</p><span class="marker MOD1 mod-inline"></span></section> <span class="marker h2"></span><section data-level="1" id="ref51802"><h2 class="h1">Classification</h2> <span class="marker PREMOD2 mod-inline"></span><p class="topic-paragraph">The definition of a <span id="ref506244"></span><a href="https://www.britannica.com/science/solid-state-of-matter" class="md-crosslink " data-show-preview="true">solid</a> appears obvious; a solid is generally thought of as being hard and firm. Upon inspection, however, the definition becomes less <a class="md-dictionary-link md-dictionary-tt-off eb" data-term="straightforward" href="https://www.britannica.com/dictionary/straightforward" data-type="EB">straightforward</a>. A cube of butter, for example, is hard after being stored in a refrigerator and is clearly a solid. After remaining on the kitchen counter for a day, the same cube becomes quite soft, and it is unclear if the butter should still be considered a solid. Many crystals behave like butter in that they are hard at low temperatures but soft at higher temperatures. They are called solids at all temperatures below their <a href="https://www.britannica.com/science/melting-point" class="md-crosslink autoxref " data-show-preview="true">melting point</a>. A possible definition of a solid is an object that retains its shape if left undisturbed. The <a class="md-dictionary-link md-dictionary-tt-off eb" data-term="pertinent" href="https://www.britannica.com/dictionary/pertinent" data-type="EB">pertinent</a> issue is how long the object keeps its shape. A highly viscous fluid retains its shape for an hour but not a year. A solid must keep its shape longer than that.</p><span class="marker MOD2 mod-inline"></span> <section data-level="2" id="ref51803"><h2 class="h2">Basic units of <span id="ref1119388"></span><a href="https://www.britannica.com/science/solid-state-of-matter" class="md-crosslink " data-show-preview="true">solids</a></h2> <span class="marker PREMOD3 mod-inline"></span><p class="topic-paragraph">The basic units of solids are either <span id="ref506246"></span><a href="https://www.britannica.com/science/atom" class="md-crosslink " data-show-preview="true">atoms</a> or atoms that have combined into molecules. The <span id="ref506247"></span><a href="https://www.britannica.com/science/electron" class="md-crosslink " data-show-preview="true">electrons</a> of an <a href="https://www.britannica.com/science/atom" class="md-crosslink autoxref " data-show-preview="true">atom</a> move in orbits that form a <span id="ref506248"></span><a href="https://www.britannica.com/science/electron-shell" class="md-crosslink " data-show-preview="true">shell</a> structure around the nucleus. The shells are filled in a systematic order, with each shell accommodating only a small number of electrons. Different atoms have different numbers of electrons, which are distributed in a characteristic <a href="https://www.britannica.com/science/electronic-configuration" class="md-crosslink autoxref " data-show-preview="true">electronic structure</a> of filled and partially filled shells. The arrangement of an atom’s electrons determines its chemical properties. The properties of solids are usually predictable from the properties of their <a class="md-dictionary-link md-dictionary-tt-off mw" data-term="constituent" href="https://www.merriam-webster.com/dictionary/constituent" data-type="MW">constituent</a> atoms and molecules, and the different shell structures of atoms are therefore responsible for the <a class="md-dictionary-link md-dictionary-tt-off mw" data-term="diversity" href="https://www.merriam-webster.com/dictionary/diversity" data-type="MW">diversity</a> of solids.</p><span class="marker MOD3 mod-inline"></span> <span class="marker PREMOD4 mod-inline"></span><p class="topic-paragraph">All occupied shells of the <span id="ref506249"></span><a href="https://www.britannica.com/science/argon-chemical-element" class="md-crosslink " data-show-preview="true">argon</a> (Ar) atom, for example, are filled, resulting in a spherical atomic shape. In solid argon the atoms are arranged according to the closest packing of these spheres. The <span id="ref506250"></span><a href="https://www.britannica.com/science/iron-chemical-element" class="md-crosslink " data-show-preview="true">iron</a> (Fe) atom, in contrast, has one <a href="https://www.britannica.com/science/electron-shell" class="md-crosslink autoxref " data-show-preview="true">electron shell</a> that is only partially filled, giving the atom a net magnetic moment. Thus, crystalline iron is a magnet. The <a href="https://www.britannica.com/science/covalent-bond" class="md-crosslink autoxref " data-show-preview="true">covalent bond</a> between two <a href="https://www.britannica.com/science/carbon-chemical-element" class="md-crosslink autoxref " data-show-preview="true">carbon</a> (C) atoms is the strongest bond found in nature. This strong bond is responsible for making <a href="https://www.britannica.com/topic/diamond-gemstone" class="md-crosslink autoxref " data-show-preview="true">diamond</a> the hardest solid.</p><span class="marker MOD4 mod-inline"></span></section> <section data-level="2" id="ref51804"><h2 class="h2"><span id="ref506251"></span><a href="https://www.britannica.com/science/long-range-order" class="md-crosslink ">Long</a>- and <span id="ref506252"></span><a href="https://www.britannica.com/science/short-range-order" class="md-crosslink ">short-range order</a></h2> <span class="marker PREMOD5 mod-inline"></span><p class="topic-paragraph">A solid is crystalline if it has long-range order. Once the positions of an atom and its neighbours are known at one point, the place of each atom is known precisely throughout the crystal. Most liquids lack long-range order, although many have short-range order. Short range is defined as the first- or second-nearest neighbours of an atom. In many liquids the first-neighbour atoms are arranged in the same structure as in the corresponding solid <a href="https://www.britannica.com/science/phase-state-of-matter" class="md-crosslink autoxref " data-show-preview="true">phase</a>. At distances that are many atoms away, however, the positions of the atoms become uncorrelated. These fluids, such as water, have short-range order but lack long-range order. Certain liquids may have short-range order in one direction and long-range order in another direction; these special substances are called <a href="https://www.britannica.com/science/liquid-state-of-matter" class="md-crosslink autoxref " data-show-preview="true">liquid</a> crystals. Solid crystals have both short-range order and long-range order.</p><div class="module-spacing"> </div><span class="marker MOD5 mod-inline"></span> <span class="marker PREMOD6 mod-inline"></span><p class="topic-paragraph">Solids that have short-range order but lack long-range order are called <span id="ref506253"></span><a href="https://www.britannica.com/science/amorphous-solid" class="md-crosslink " data-show-preview="true">amorphous</a>. Almost any material can be made <a class="md-dictionary-link md-dictionary-tt-off mw" data-term="amorphous" href="https://www.merriam-webster.com/dictionary/amorphous" data-type="MW">amorphous</a> by rapid solidification from the melt (molten state). This condition is unstable, and the solid will crystallize in time. If the timescale for crystallization is years, then the amorphous state appears stable. Glasses are an example of amorphous solids. In crystalline <span id="ref506254"></span><a href="https://www.britannica.com/science/silicon" class="md-crosslink " data-show-preview="true">silicon</a> (Si) each atom is tetrahedrally bonded to four neighbours. In <span id="ref506255"></span><a href="https://www.britannica.com/science/amorphous-silicon" class="md-crosslink ">amorphous silicon</a> (a-Si) the same short-range order exists, but the bond directions become changed at distances farther away from any atom. Amorphous silicon is a type of <a href="https://www.britannica.com/technology/glass" class="md-crosslink autoxref " data-show-preview="true">glass</a>. Quasicrystals are another type of solid that lack long-range order.</p><span class="marker MOD6 mod-inline"></span> <span class="marker PREMOD7 mod-inline"></span><p class="topic-paragraph">Most solid materials found in nature exist in <span id="ref506256"></span><a href="https://www.britannica.com/science/polycrystal" class="md-crosslink " data-show-preview="true">polycrystalline</a> form rather than as a <a href="https://www.britannica.com/science/single-crystal" class="md-crosslink autoxref " data-show-preview="true">single crystal</a>. They are actually composed of millions of grains (small crystals) packed together to fill all space. Each individual <a href="https://www.britannica.com/science/grain-solid" class="md-crosslink autoxref " data-show-preview="true">grain</a> has a different orientation than its neighbours. Although long-range order exists within one grain, at the boundary between grains, the ordering changes direction. A typical piece of iron or copper (Cu) is polycrystalline. Single crystals of metals are soft and <a class="md-dictionary-link md-dictionary-tt-off mw" data-term="malleable" href="https://www.merriam-webster.com/dictionary/malleable" data-type="MW">malleable</a>, while polycrystalline metals are harder and stronger and are more useful industrially. Most polycrystalline materials can be made into large single crystals after extended <a href="https://www.britannica.com/technology/heat-treating" class="md-crosslink autoxref " data-show-preview="true">heat treatment</a>. In the past blacksmiths would heat a piece of <a href="https://www.britannica.com/science/metal-chemistry" class="md-crosslink autoxref " data-show-preview="true">metal</a> to make it malleable: heat makes a few grains grow large by incorporating smaller ones. The smiths would bend the softened metal into shape and then pound it awhile; the pounding would make it polycrystalline again, increasing its strength.</p><div class="module-spacing"> <DIV class="marketing-INLINE_SUBSCRIPTION marketing-content" data-marketing-id="INLINE_SUBSCRIPTION"><style> .student-promo-banner-wrapper { container-type: inline-size; margin-bottom: 15px; } @container (min-width: 475px) { .student-promo-banner { flex-direction: row; } .student-promo-banner-img-wrapper { margin-bottom: 0; margin-right: 10px; justify-content: flex-start; } .student-promo-banner-text-wrapper { text-align: left; margin-bottom: 0px; margin-left: 10px; } .student-promo-banner-button-wrapper { margin-right: 0; } }</style> <div class="student-promo-banner-wrapper"> <div class="student-promo-banner d-flex flex-column align-items-center bg-blue rounded p-20"> <div class="student-promo-banner-img-wrapper mb-20 mr-0 d-flex justify-content-center"> <img class="rounded" style="max-width: 100px; min-width: 80px" src="https://cdn.britannica.com/marketing/BlueThistle.webp" /> </div> <div class="student-promo-banner-text-wrapper ml-0 mb-10 text-center text-white"> <div class="h2 mb-10">Get Unlimited Access</div> <div class="h4 font-weight-semi-bold">Try Britannica Premium for free and discover more.</div> </div> <div class="student-promo-banner-button-wrapper d-flex justify-content-center align-items-center ml-auto mr-auto"> <a class="btn btn-m btn-orange" href="https://premium.britannica.com/premium-membership/?utm_source=premium&utm_medium=inline-cta&utm_campaign=black-friday-2024">Subscribe</a> </div> </div> </div> </DIV></div><div class="one-good-fact-module"> </div><span class="marker MOD7 mod-inline"></span></section> <section data-level="2" id="ref51805"><h2 class="h2">Categories of crystals</h2> <span class="marker PREMOD8 mod-inline"></span><p class="topic-paragraph">Crystals are classified in general categories, such as insulators, metals, semiconductors, and molecular solids. A single crystal of an insulator is usually <a class="md-dictionary-link md-dictionary-tt-off eb" data-term="transparent" href="https://www.britannica.com/dictionary/transparent" data-type="EB">transparent</a> and resembles a piece of glass. Metals are shiny unless they have rusted. Semiconductors are sometimes shiny and sometimes transparent but are never rusty. Many crystals can be classified as a single type of solid, while others have intermediate behaviour. <span id="ref506257"></span><a href="https://www.britannica.com/science/cadmium-sulfide" class="md-crosslink ">Cadmium sulfide</a> (CdS) can be prepared in pure form and is an excellent insulator; when impurities are added to cadmium sulfide, it becomes an interesting <a href="https://www.britannica.com/science/semiconductor" class="md-crosslink autoxref " data-show-preview="true">semiconductor</a>. <span id="ref506258"></span><a href="https://www.britannica.com/science/bismuth" class="md-crosslink " data-show-preview="true">Bismuth</a> (Bi) appears to be a metal, but the number of electrons available for electrical conduction is similar to that of semiconductors. In fact, bismuth is called a semimetal. Molecular solids are usually crystals formed from molecules or polymers. They can be insulating, semiconducting, or metallic, depending on the type of molecules in the crystal. New molecules are continuously being <a class="md-dictionary-link md-dictionary-tt-off eb" data-term="synthesized" href="https://www.britannica.com/dictionary/synthesized" data-type="EB">synthesized</a>, and many are made into crystals. The number of different crystals is enormous.</p><span class="marker MOD8 mod-inline"></span></section></section> <span class="marker end-of-content"></span><span class="marker after-article"></span></div> <div id="chatbot-root"></div> </div> </div> </div> <div class="ai-dialog-placeholder"></div> </div> </div> <aside class="col-md-da-320"></aside> </div> </div> </div> </div> </article></div> </div></div> </div> </main> <div id="md-footer"></div> <noscript><iframe src="//www.googletagmanager.com/ns.html?id=GTM-5W6NC8" height="0" width="0" style="display:none;visibility:hidden"></iframe></noscript> <script type="text/javascript" id="_informizely_script_tag"> var IzWidget = IzWidget || {}; (function (d) { var scriptElement = d.createElement('script'); scriptElement.type = 'text/javascript'; scriptElement.async = true; scriptElement.src = "https://insitez.blob.core.windows.net/site/f780f33e-a610-4ac2-af81-3eb184037547.js"; var node = d.getElementById('_informizely_script_tag'); node.parentNode.insertBefore(scriptElement, node); } )(document); </script>  <script> window.ap3c = window.ap3c || {}; var ap3c = window.ap3c; ap3c.cmd = ap3c.cmd || []; ap3c.cmd.push(function() { ap3c.init('ZO4siT4cLwnykPnzZWJtd3Byb2Q', 'https://engage.email.britannica.com/'); ap3c.track({v: 0}); }); ap3c.activity = function(act) { ap3c.act = (ap3c.act || []); ap3c.act.push(act); }; var s, t; s = document.createElement('script'); s.type = 'text/javascript'; s.src = "https://engage.email.britannica.com/app.js"; t = document.getElementsByTagName('script')[0]; t.parentNode.insertBefore(s, t); </script> <script class="marketing-page-info" type="application/json"> {"pageType":"Topic","templateName":"DESKTOP","pageNumber":1,"pagesTotal":10,"pageId":145105,"pageLength":972,"initialLoad":true,"lastPageOfScroll":false} </script> <script class="marketing-content-info" type="application/json"> [] </script> <script src="https://cdn.britannica.com/mendel-resources/3-130/js/libs/jquery-3.5.0.min.js?v=3.130.14"></script> <script type="text/javascript" data-type="Init Mendel Code Splitting"> (function() { $.ajax({ dataType: 'script', cache: true, url: 'https://cdn.britannica.com/mendel-resources/3-130/dist/topic-page.js?v=3.130.14' }); })(); </script> <script class="analytics-metadata" type="application/json"> {"leg":"B","adLeg":"B","userType":"ANONYMOUS","pageType":"Topic","pageSubtype":null,"articleTemplateType":"PAGINATED","gisted":false,"pageNumber":1,"hasSummarizeButton":false,"hasAskButton":false} </script> <script type="text/javascript"> EBStat={accountId:-1,hostnameOverride:'webstats.eb.com',domain:'www.britannica.com', json:''}; </script> <script type="text/javascript"> ( function() { $.ajax( { dataType: 'script', cache: true, url: '//www.britannica.com/webstats/mendelstats.js?v=1' } ) .done( function() { try {writeStat(null,EBStat);} catch(err){} } ); })(); </script> <div id="bc-fixed-dialogue"></div> </body> </html>

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Crystal | Definition, Types, Structure, & Facts | Britannica