26 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>Tectosilicate</h2> Subject The topic of the resource <p>Framework silicate.</p> https://wserv3.esc.cam.ac.uk/p1acollections/files/original/12b5c18a74215d375e002f21037f4df9.jpg 113d76f170e53159aa1248482d0c7b82 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>Tourmaline</h2> Subject The topic of the resource <span>Tourmaline is the only common mineral of which boron is an essential constituent. Its presence in a rock, therefore, indicates that the rock contains significant boron. </span> Description An account of the resource <div class="element"> <h3>Formula</h3> <div class="element-text">(Na,Ca)(Mg,Fe,Mn,Li,Al)₃(Al,Mg,Fe³⁺)₆[Si₆O₁₈](BO₃)₃(O,OH)₃(OH,F)</div> </div> <div class="element"> <h3>Structure</h3> <div class="element-text"> <p>Ring silicate</p> </div> </div> <div class="element"> <h3>Crystal System</h3> <div class="element-text"> <p><em>Crystal system:</em><span> </span>trigonal (-)</p> </div> </div> <div class="element"> <h3>Physical Properties</h3> <div class="element-text"> <p><em>Colour in hand specimen:</em><span> </span>black<br /><em>Hardness:</em><span> </span>7</p> </div> </div> <div class="element"> <h3>Optical Properties</h3> <div class="element-text"> <p><em>Colour in plane polarised light:</em><span> </span>typically brown-green or green<br /><em>Pleochroism:</em><span> </span>strongly pleochroic in many colours<br /><em>Relief:</em><span> </span>moderate<br /><em>Birefringence:</em><span> </span>typically 2nd order</p> </div> </div> <div class="element"> <h3>Rock Specimens</h3> <div class="element-text"> <p><a href="/p1acollections/exhibits/show/metamorphic-rocks/l504">L504 Garnet schist</a></p> </div> </div> <div class="element"> <h3>Mineral Name</h3> <div class="element-text">tourmaline</div> </div> granite metapelite pegmatite https://wserv3.esc.cam.ac.uk/p1acollections/files/original/dc11da9eedee656b100d0aa3d446e9eb.png d6dda441db8598e76b1e024b62470847 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>Trilobite</h2> Description An account of the resource <h2>Taxonomy</h2> <p>Phylum: Arthropoda</p> <p>Class: Trilobita</p> <h2>Distinctive features</h2> <p>Pygidium (tail)</p> <p>Thorax (body)</p> <p>Cephalon (head)</p> <p>Paired appendages (not often preserved)</p> <p>Three lobed longitudinal division of body (2x pleural, 1x axial)</p> <p>Calcitic exoskeleton</p> <p>Segmented body</p> <p>Glabella</p> <p>Eyes (holochroal or schizochroal; only present in some groups)</p> <p>Eye ridges</p> <p>Occipital ring</p> <p>Axial rings</p> <h2>Stratigraphic range</h2> <p>Cambrian to Permian (most common Cambrian to Silurian)</p> <h2>Way of life</h2> <p>Trilobites lived as planktonic, nektonic, epifaunal and infaunal organisms in deep and shallow marine environments. They lived as predators, filter feeders, deposit feeders, particle feeders, scavengers and even symbiotically.</p> <p>By looking at the functional morphology of the trilobite in question you can be more specific about how it lived, by looking at body shape, size, legs, eyes and other characters.</p> <h2>Advanced notes</h2> <p>Trilobites were very abundant during the Palaeozoic. Their preservation potential was increased further as they moulted their exoskeletons periodically as they grew. This means that one trilobite left numerous hard skeletons or partial skeletons as it grew, each of which has the potential to fossilise.</p> <h2>Specimens</h2> <p><a href="/p1acollections/exhibits/show/trilobites" target="_blank" rel="noreferrer noopener">Browse trilobites</a></p> <h2>Links</h2> <p><a href="https://www.digitalatlasofancientlife.org/learn/nature-fossil-record/types-of-fossil-preservation/">Learn about types of preservation</a></p> 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>Turbidite</h2> Subject The topic of the resource Sedimentary rock structure characterised by a fining-up sequence. They are produced by turbidity flows. 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>Twinning</h2> Subject The topic of the resource Within a single mineral grain the crystal lattice may be oriented differently on either side of a plane, or twin plane. Thus the grain will go into extinction at different positions on either side of the twin plane. This is twinning. 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>Undulose extinction</h2> Subject The topic of the resource If some areas of a mineral grain have different extinction positions from other areas of the same grain, the grain is said to display undulose extinction. Importantly, there is no sharp division between areas with different extinction positions; otherwise the phenomenon could be due to twinning. Undulose extinction is frequently observed in strained quartz, where the crystal lattice has been distorted by being squeezed. Description An account of the resource <em>Have a look at the <strong>ferruginous sandstone (<a href="https://wserv3.esc.cam.ac.uk/p1acollections/items/show/26">L327</a>) </strong>and the<strong> quartzite (<a href="https://wserv3.esc.cam.ac.uk/p1acollections/items/show/40">L521</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>Vesicular</h2> Subject The topic of the resource Igneous rocks with a vesicular texture contain air bubbles, called vesicles. These can be round or distorted. In thin-section, vesicles are filled with the mounting medium and consequently appear clear and colourless with low relief under plain polarised light. They are isotropic. Vesicles which are infilled with precipitated minerals, such as calcite or quartz are called amygdales. Description An account of the resource Have a look at the rhyolitic glass (<a href="https://wserv3.esc.cam.ac.uk/p1acollections/items/show/7">L113</a>) and the porphyritic andesite (<a href="https://wserv3.esc.cam.ac.uk/p1acollections/items/show/9">L130</a>) in the 1A Reference Series. 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>Vitreous [lustre]</h2> Subject The topic of the resource Minerals displaying a glass-like lustre are described as vitreous. These minerals are transparent or translucent and have relatively low refractive indices. Quartz and calcite, for example, have vitreous lustre. Description An account of the resource Have a look at <a href="https://wserv3.esc.cam.ac.uk/p1acollections/items/show/57">quartz</a> (M410, M411, M412) and <a href="https://wserv3.esc.cam.ac.uk/p1acollections/items/show/64">calcite</a> (M540, M541, M542) in the Reference Series. 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>Volcanic</h2> Subject The topic of the resource Volcanic rocks and textures are those associated with magmatic eruptions at the surface of the Earth. These eruptions can occur into air, water or ice. In each case cooling is very rapid, causing fine-grained textures to develop. https://wserv3.esc.cam.ac.uk/p1acollections/files/original/5e37a66fc246f7e8a088a4e4c0d011bd.jpg 541861a9fa9a4ae459f66f0e9c425bb3 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>Zircon</h2> Description An account of the resource <div class="element-set"> <div class="element"> <div class="element-text"> <h3>Formula</h3> </div> </div> </div> <div class="element-set"> <div class="element"> <div class="element-text">Zr[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>tetragonal (+)</p> </div> </div> <div class="element"> <h3>Physical Properties</h3> <div class="element-text"> <p><em>Colour in hand specimen:</em><span> </span>reddish brown, yellow, grey, green or colourless<br /><em>Hardness:</em><span> </span>7.5</p> </div> </div> <div class="element"> <h3>Optical Properties</h3> <div class="element-text"> <p><em>Colour in plane polarised light:</em> colourless to pale brown<span> </span><br /><em>Pleochroism:</em> very weak<br /><em>Relief:</em> high<br /><em>Birefringence:</em> 0.042-0.065; 3rd order green to 4th order green<br /><em>Extinction:</em> straight<br /><em>Twinning:</em> rare</p> </div> </div> <div class="element"> <h3>Rock Specimens</h3> <div class="element-text"> <p><a href="/p1acollections/exhibits/show/igneous-rocks/l100">L100 Alkali granite</a></p> </div> </div> <div class="element"> <h3>Mineral Name</h3> <div class="element-text">zircon</div> </div> </div> Subject The topic of the resource Zircon is a common accessory mineral of many igneous rocks. Pleochroic haloes are formed by damage to the crystal lattice of enclosing minerals by the radioactive decay of elements such as Th and U in zircon. These may be particularly noticeable in biotite grains in old granitic rocks. granite radiation thorium uranium