1 10 1 https://wserv3.esc.cam.ac.uk/p1acollections/files/original/be33d89fe6d9036ae8352a6f3f9a84ad.jpg c11d5dd9223d779156b594135bba0756 https://wserv3.esc.cam.ac.uk/p1acollections/files/original/6674f7f49c2139327e03ef9b7487f568.jpg 434535ac740cdd1dd8093026a4e67be7 Physical Object An inanimate, three-dimensional object or substance. Note that digital representations of, or surrogates for, these objects should use Moving Image, Still Image, Text or one of the other types. Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource <h2>Amphibole (hornblende)</h2> Description An account of the resource <div class="element"> <h3>Formula</h3> <div class="element-text"> <p>(Na,K)_0-1Ca₂(Mg,Fe²⁺,Fe³⁺,Al)₅Si_6-7.5Al_2-0.5O₂₂(OH)₂</p> </div> </div> <div class="element"> <h3>Structure</h3> <div class="element-text"> <p>Chain silicate</p> </div> </div> <div class="element"> <h3>Crystal System</h3> <div class="element-text"> <p class="NoSpacing"><em><span>Crystal</span></em><em><span> system: </span></em><span>monoclinic (+) (-)</span></p> </div> </div> <div class="element"> <h3>Physical Properties</h3> <div class="element-text"> <p class="NoSpacing"><em><span>Colour in hand specimen:</span></em><span> black</span><span> </span><br class="NoSpacing" /><em><span>Cleavage:</span></em><span> two at ~56°</span><span> </span><br class="NoSpacing" /><em><span>Hardness:</span></em><span> 5-6</span></p> </div> </div> <div class="element"> <h3>Optical Properties</h3> <div class="element-text"> <p class="NoSpacing"><em><span>Colour in plane polarised light:</span></em><span> pale green, green, light yellow-brown to brown</span><span> </span><br class="NoSpacing" /><em><span>Pleochroism:</span></em><span> yes</span><span> </span><br class="NoSpacing" /><em><span>Relief:</span></em><span> moderate</span><span> </span><br class="NoSpacing" /><em><span>Birefringence:</span></em><span> ~0.02; 2^nd order purple</span><span> </span><br class="NoSpacing" /><em><span>Extinction:</span></em><span> inclined</span><span> </span><br class="NoSpacing" /><em><span>Twinning:</span></em><span> simple, lamellar, common</span></p> </div> </div> <div class="element"> <h3>Mineral Specimens</h3> <div class="element-text"> <p><strong><span>M210 </span></strong><strong><span>Amphibole, hornblende</span></strong><span> </span><br /><strong>Bilen, Bohemia</strong><span> </span><br />Single, black prismatic<strong><span> </span></strong>crystal.<span> </span><br />At the ends of the crystal two sets of cleavage planes are visible, intersecting at ~56°</p> <p><strong><span>M211 </span></strong><strong><span>Amphibolite</span></strong><span> </span><br /><strong>Isle of Coll, Inner Hebrides</strong><span> </span><br />A metamorphic rock consisting almost entirely of crystals of the amphibole hornblende<span> </span><br />Black<span> </span><br />Brilliant lustre<span> </span><br />Two sets of cleavage planes intersect at ~56°</p> </div> </div> <div class="element"> <h3>Rock Specimens</h3> <div class="element-text"> <p><a href="/p1acollections/exhibits/show/igneous-rocks/l102">L102 Hornblende biotite granite</a><span> </span><br /><a href="/p1acollections/exhibits/show/igneous-rocks/l120">L120 Granodiorite</a></p> </div> </div> <div class="element"> <h3>Advanced Notes</h3> <div class="element-text"> <p class="NoSpacing"><span>The amphibole group encompasses a wide range of compositions. Even the hornblendes, which are a sub-group of the amphiboles, encompass a range of compositions (see mineral formula, above). The properties above refer to hornblende.</span></p> </div> </div> <div class="element"> <h3>Mineral Name</h3> <div class="element-text">amphibole<br />hornblende</div> </div> igneous metabasite