22 10 264 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/. Description An account of the resource This glossary describes a number of geological terms with which the 1A students should become familiar.<span> It is by no means an exhaustive list, but is aimed to help you understand the material within the first year course.</span> Title A name given to the resource Glossary 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>Microcrystalline</h2> Subject The topic of the resource Rocks with a crystalline structure in which the individual crystals cannot be identified by the naked eye, but are large enough to be identified using standard optical microscopy are described as microcrystalline. Description An account of the resource <div> <div class="element-set"> <div class="element"> <div class="element-text"> <p><em>Compare with<span> </span><a href="https://wserv3.esc.cam.ac.uk/p1acollections/items/show/184">cryptocrystalline</a>.</em></p> </div> </div> </div> </div> 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/. Description An account of the resource This glossary describes a number of geological terms with which the 1A students should become familiar.<span> It is by no means an exhaustive list, but is aimed to help you understand the material within the first year course.</span> Title A name given to the resource Glossary 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>Microperthite texture</h2> Subject The topic of the resource Parallel lamellae or trains of blebs of one mineral, all in the same optical orientation, are enclosed in a single “host” crystal of another mineral. This texture is generally attributed to solid-state exsolution of the daughter phase from the host. Description An account of the resource <em>Have a look at the <strong>alkali granite (<a href="https://wserv3.esc.cam.ac.uk/p1acollections/items/show/1">L100</a>)</strong> and the <strong>hornblende biotite granite (<a href="https://wserv3.esc.cam.ac.uk/p1acollections/items/show/4">L102</a>)</strong> in the 1A Reference Series.</em> 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/. Description An account of the resource This glossary describes a number of geological terms with which the 1A students should become familiar.<span> It is by no means an exhaustive list, but is aimed to help you understand the material within the first year course.</span> Title A name given to the resource Glossary 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>Mohs scale</h2> Subject The topic of the resource Mineral hardness is described using the Mohs scale. The scale runs from very soft at 0 up to very hard at 10. The positions of minerals are determined by their relative hardness. For example, quartz can scratch calcite, but calcite cannot scratch quartz. Thus quartz is harder than calcite. https://wserv3.esc.cam.ac.uk/p1acollections/files/original/e36a8c8a1389dbf0209647d40c976b80.png 58b03cc689e998b264bed6110477c2f8 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 Fossils Description An account of the resource <p>Welcome to the fossils section of the website. This is designed to help you learn the different characteristics of each major fossil group so that you are able to distinguish between them.</p> <p>First year students, please refer to the specimens housed in the first year teaching laboratory. There is no substitute for handling the specimens themselves; this website is just an accessory to help you along the way.</p> <p>Animals occupy different environments, have different life habits and lived through different periods in geological time. It is good to be aware of these differences in lifestyle and timing, within and between phyla, classes, orders and families.</p> 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>Nautiloid</h2> Description An account of the resource <h2>Taxonomy</h2> <p>Phylum: Mollusca</p> <p>Class: Cephalopoda</p> <h2>Diagnostic features</h2> <p>Simple suture</p> <p>Chambers</p> <p>Central siphuncle</p> <p>Straight, curved or coiled shell</p> <h2>Stratigraphic range</h2> <p>Cambrian to recent</p> <p>Straight forms: Cambrian to Permian</p> <p>Coiled forms: Devonian to Present</p> <h2>Way of life</h2> <span>Nektonic (jet propulsion)</span><br /><p>Predatory</p> <p>Buoyancy controlled by changing gas/liquid contents of chambers</p> <p>Marine</p> <h2>Preservation</h2> <p>Commonly preserved as internal moulds</p> <p>Modern<span> </span><em></em>nautiloids preserved with original shell material</p> <p><a href="https://www.digitalatlasofancientlife.org/learn/nature-fossil-record/types-of-fossil-preservation/">Learn about types of preservation</a></p> <h2>Advanced notes</h2> <p>Nautiloids originated in the Cambrian period, and radiated during the Ordovician. These early nautiloids had conical shaped shells. In the Silurian some nautiloids used curved shells, and by the Devonian some were coiled. The evolution of the coiled shell from the straight is thought to be driven, at least in part, by increased mobility of a coiled shell compared to a long straight one.</p> <p>Nautiloids could be confused with ammonoids. You can distinguish them by the location of the siphuncle and the complexity of the suture pattern. Nautiloids, unlike ammonoids, are not extinct, although only six species remain today (compared to thousands in the Palaeozoic). This means that if presented with modern shell material it is likely a nautiloid and not an ammonoid.</p> <h2>Specimens</h2> <p><a href="/p1acollections/exhibits/show/nautiloids">Browse nautiloids</a></p> <h2>External links</h2> <p><a href="https://www.youtube.com/watch?v=2ilSDcZAXNM" target="_blank" rel="noreferrer noopener">Telling planispiral fossils apart</a></p> nektonic https://wserv3.esc.cam.ac.uk/p1acollections/files/original/c48647ef4bdeaab9cd06257b506e7ba5.jpg 9f81309144388bca4172f5e94f4d8974 https://wserv3.esc.cam.ac.uk/p1acollections/files/original/1bccc279a78201775346b3920b73c491.jpg bc43e3bafb84ae9faba453d6169d411a 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>Olivine</h2> Description An account of the resource <div class="element"> <h3>Formula</h3> <div class="element-text">(Mg,Fe)₂[SiO₄]</div> </div> <div class="element"> <h3>Structure</h3> <div class="element-text"> <p>Orthosilicate</p> </div> </div> <div class="element"> <h3>Crystal System</h3> <div class="element-text"> <p><em>Crystal system:</em><span> </span>orthorhombic (+) (-)</p> </div> </div> <div class="element"> <h3>Physical Properties</h3> <div class="element-text"> <p><em>Colour in hand specimen:</em> pale green<br /><em>Cleavage: </em>none, instead it has characteristic curving cracks<em><br />Hardness:</em> 7</p> </div> </div> <div class="element"> <h3>Optical Properties</h3> <div class="element-text"> <p><em>Colour in plane polarised light:</em> colourless<br /><em>Relief:</em> moderate <br /><em>Birefringence:</em> 0.035; 2nd order pink</p> </div> </div> <div class="element"> <h3>Mineral Specimens</h3> <div class="element-text"> <p><strong><span>M100 Olivine</span><span> </span><br />North Carolina</strong><span> </span><br />A mass of rather irregular crystals of olivine<br />Yellow-green colour<br />Vitreous lustre<br />No cleavage</p> </div> </div> <div class="element"> <h3>Rock Specimens</h3> <div class="element-text"> <p><a href="/p1acollections/exhibits/show/igneous-rocks/l141">L141 Gabbro</a><span> </span><br /><a href="/p1acollections/exhibits/show/igneous-rocks/l162">L162 Basalt, porphyritic</a><span> </span><br /><a href="/p1acollections/exhibits/show/igneous-rocks/l172">L172 Ultramafic cumulate</a></p> </div> </div> <div class="element"> <h3>Advanced Notes</h3> <div class="element-text">Olivine has two end-member compositions: forsterite, Mg₂[SiO₄], and fayalite, Fe₂[SiO₄]. The physical and optical properties detailed above refer to forsterite<strong>.</strong><span> </span>Forsteritic olivine is a common constituent of mafic and ultra-mafic rocks.<br />Cracks are often filled with serpentinite alteration.</div> </div> <div class="element"> <h3>Mineral Name</h3> <div class="element-text">olivine<br />forsterite<br />fayallite</div> </div> mafic 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/. Description An account of the resource This glossary describes a number of geological terms with which the 1A students should become familiar.<span> It is by no means an exhaustive list, but is aimed to help you understand the material within the first year course.</span> Title A name given to the resource Glossary 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>Ooid</h2> Subject The topic of the resource Sub-spherical sedimentary grains comprising a nucleus surrounded by concentric layers of carbonate precipitate. Ooids form abiogenically. They are sometimes referred to as ooliths. Description An account of the resource <em>Have a look at the <strong>oolitic ironstone (<a href="https://wserv3.esc.cam.ac.uk/p1acollections/items/show/34">L361</a>) </strong>and the<strong> oolitic limestone (<a href="https://wserv3.esc.cam.ac.uk/p1acollections/items/show/32">L353</a>)</strong> in the 1A Reference Series.</em> https://wserv3.esc.cam.ac.uk/p1acollections/files/original/6a2fdeca2774e679a0153821edf123e9.jpg 6a17bfc2d428df30b504c9506a7bb23a https://wserv3.esc.cam.ac.uk/p1acollections/files/original/2711ba062a08634b610c1cdd18f67fcc.jpg 7f450bfca482d0fe4649c3f6f70d4afa 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>Orthopyroxene</h2> Description An account of the resource <div class="element"> <h3>Formula</h3> <div class="element-text">(Mg,Fe)₂Si₂O₆</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><em>Crystal system:</em><span> </span>orthorhombic (+) (-)</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><br class="NoSpacing" /><em><span>Cleavage:</span></em><span> two at 90°</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>colourless, reddish or greenish </span><br class="NoSpacing" /><em><span>Pleochroism:</span></em><span> variable weak to strong</span><span> </span><br class="NoSpacing" /><em><span>Relief:</span></em><span> moderate </span><br class="NoSpacing" /><em><span>Birefringence:</span></em><span> 0.007-0.020; 1^st order grey to 2^nd order purple</span><span> </span><br class="NoSpacing" /><em><span>Extinction: </span></em><span>straight</span></p> </div> </div> <div class="element"> <h3>Advanced Notes</h3> <div class="element-text"> <p class="NoSpacing"><span>Orthopyroxene has two end-member compositions: enstatite, Mg₂Si₂O₆, and ferrosilite, Fe²⁺₂Si₂O₆.</span></p> </div> </div> <div class="element"> <h3>Mineral Name</h3> <div class="element-text">orthopyroxene</div> </div> mafic 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/. Description An account of the resource This glossary describes a number of geological terms with which the 1A students should become familiar.<span> It is by no means an exhaustive list, but is aimed to help you understand the material within the first year course.</span> Title A name given to the resource Glossary 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>Orthosilicate</h2> Subject The topic of the resource <span>Silicate minerals in which the SiO4 tetrahedra do not share oxygen atoms with one another are called orthosilicates, or island silicates. These minerals do not contain bridging oxygen atoms.</span> 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/. Description An account of the resource This glossary describes a number of geological terms with which the 1A students should become familiar.<span> It is by no means an exhaustive list, but is aimed to help you understand the material within the first year course.</span> Title A name given to the resource Glossary 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>Overgrowth</h2> Subject The topic of the resource The crystallisation of one mineral on the surface of another, producing a rim or part of a rim. 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/. Description An account of the resource This glossary describes a number of geological terms with which the 1A students should become familiar.<span> It is by no means an exhaustive list, but is aimed to help you understand the material within the first year course.</span> Title A name given to the resource Glossary 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>Pearly [lustre]</h2> Subject The topic of the resource <span>Unsurprisingly the quality and intensity of light reflected from minerals displaying “pearly” lustre is reminiscent of pearls. This effect is produced by the reflection of light from many thin, coplanar, transparent sheets within the mineral. Muscovite, for example, has pearly lustre.</span> Description An account of the resource <em>Have a look at the <strong><a href="https://wserv3.esc.cam.ac.uk/p1acollections/items/show/51">muscovite mica</a> (M301, M302)</strong> in the 1A Reference Series.</em>