<span class="mw-page-title-main">Optical mineralogy</span>

This article is largely based on an article  in the out-of-copyright Encyclopædia Britannica Eleventh Edition, which was produced in 1911. It should be brought up to date to reflect subsequent history or scholarship (including the references, if any). When you have completed the review, replace this notice with a simple note on this article's talk page.  (January 2011)

Optical mineralogy

<p><b>Optical mineralogy</b> is the study of <a href="/en/Mineral" title="Mineral" class="wl">minerals</a> and <a href="/en/Rock_(geology)" title="Rock (geology)" class="wl">rocks</a> by measuring their <a href="/en/Optics" title="Optics" class="wl">optical</a> properties. Most commonly, rock and mineral samples are prepared as <a href="/en/Thin_section" title="Thin section" class="wl">thin sections</a> or grain mounts for study in the <a href="/en/Laboratory" title="Laboratory" class="wl">laboratory</a> with a <a href="/en/Petrographic_microscope" title="Petrographic microscope" class="wl">petrographic microscope</a>. Optical mineralogy is used to identify the mineralogical composition of geological materials in order to help reveal their origin and evolution.</p>

<div class="shortdescription nomobile noexcerpt noprint searchaux" style="display:none" about="#mwt1">Optical properties of rocks and minerals</div>
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<figure class="mw-default-size mw-halign-right wiki-thumb"><a href="/en/File:Leica_DMRX.jpg" class="mw-file-description image media-thumb" data-hash="File:Leica_DMRX.jpg"><img loading="lazy" src="//upload.wikimedia.org/wikipedia/commons/thumb/d/d2/Leica_DMRX.jpg/220px-Leica_DMRX.jpg" decoding="async" data-file-width="234" data-file-height="312" data-file-type="bitmap" height="293" width="220" srcset="//upload.wikimedia.org/wikipedia/commons/d/d2/Leica_DMRX.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/d/d2/Leica_DMRX.jpg 2x" alt="Leica_DMRX.jpg"></a><figcaption>A <a href="/en/Petrographic_microscope" title="Petrographic microscope" class="wl">petrographic microscope</a>, which is an <a href="/en/Optical_microscope" title="Optical microscope" class="wl">optical microscope</a> fitted with cross-<a href="/en/Polarizer" title="Polarizer" class="wl">polarizing</a> lenses, a <a href="/en/Conoscopy" title="Conoscopy" class="wl">conoscopic lens</a>, and compensators (plates of anisotropic materials; gypsum plates and quartz wedges are common), for crystallographic analysis.</figcaption></figure>

<p>Some of the properties and techniques used include:</p>
<ul><li><a href="/en/Refractive_index" title="Refractive index" class="wl">Refractive index</a></li>
<li><a href="/en/Birefringence" title="Birefringence" class="wl">Birefringence</a></li>
<li><a href="/en/Auguste_Michel-Lévy" title="Auguste Michel-Lévy" class="wl">Michel-Lévy</a> <a href="/en/Interference_colour_chart" title="Interference colour chart" class="wl">Interference colour chart</a></li>
<li><a href="/en/Pleochroism" title="Pleochroism" class="wl">Pleochroism</a></li>
<li><a href="/en/Extinction_angle" title="Extinction angle" class="mw-redirect wl">Extinction angle</a></li>
<li><a href="/en/Conoscopic_interference_pattern" title="Conoscopic interference pattern" class="wl">Conoscopic interference pattern</a> (Interference figure)</li>
<li><a href="/en/Becke_line_test" title="Becke line test" class="wl">Becke line test</a></li>
<li><a href="/en/Optical_relief" title="Optical relief" class="wl">Optical relief</a></li>
<li><span class="new">Sign of elongation</span> (Length fast vs. length slow)<span class="mw-ref reference" id="cite_ref-1"><a href="#cite_note-1" style="counter-reset: mw-Ref 1;"><span class="mw-reflink-text">[1]</span></a></span></li>
<li><a href="/en/Wave_plate" title="Wave plate" class="mw-redirect wl">Wave plate</a></li></ul>



Optical mineralogy is the study of minerals and rocks by measuring their optical properties. Most commonly, rock and mineral samples are prepared as thin sections or grain mounts for study in the laboratory with a petrographic microscope. Optical mineralogy is used to identify the mineralogical composition of geological materials in order to help reveal their origin and evolution. Some of the properties and techniques used include: 