1 10 6 https://wserv3.esc.cam.ac.uk/p1acollections/files/original/2f7362a5c5cc5e00bc17ca856238ee37.jpg 44db79a97ef535c74d897e9db008bca0 https://wserv3.esc.cam.ac.uk/p1acollections/files/original/94761134fac46b7078906210b5bb3b8f.jpg 323c8b77db6400b701b97ff8bcaa92f2 https://wserv3.esc.cam.ac.uk/p1acollections/files/original/de6097beca8b60a758b218148982f48d.jpg cc38a8962e52d9ea6bf655b0c40038cd 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>Plagioclase feldspar</h2> Description An account of the resource <div class="element"> <h3>Formula</h3> <div class="element-text"> <p>Na[AlSi₃O₈] – Ca[Al₂Si₂O₈]</p> </div> </div> <div class="element"> <h3>Structure</h3> <div class="element-text"> <p>Framework silicate</p> </div> </div> <div class="element"> <h3>Crystal System</h3> <div class="element-text"> <p><em>Crystal system:</em><span> </span>triclinic (+) (-)</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> white</span><span> </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> 6-6.5</span></p> </div> </div> <div class="element"> <h3>Optical Properties</h3> <div class="element-text"> <p class="NoSpacing"><em>Colour in plane polarised light:</em><span> </span>colourless<span> </span><br class="NoSpacing" /><em>Pleochroism:</em><span> </span>none<span> </span><br class="NoSpacing" /><em>Relief:</em><span> </span>low<span> </span><br class="NoSpacing" /><em>Birefringence:</em><span> </span>~0.010, 1^st<span> </span>order grey<span> </span><br class="NoSpacing" /><em>Extinction:</em><span> </span>inclined<span> </span><br class="NoSpacing" /><em>Twinning:</em><span> </span>lamellar, very common</p> </div> </div> <div class="element"> <h3>Mineral Specimens</h3> <div class="element-text"> <p class="NoSpacing"><strong><span>M403 </span></strong><strong><span>Plagioclase feldspar, oligoclase</span></strong><span> </span><br class="NoSpacing" /><strong>Ytterby</strong><strong>, Sweden</strong><strong></strong><span> </span><br class="NoSpacing" />A cleavage fragment of white plagioclase feldspar<span> </span><br class="NoSpacing" />Pearly lustre on cleavage planes<span> </span><br class="NoSpacing" />Two sets of cleavage at 90°<span> </span><br class="NoSpacing" />Fine parallel striations due to lamellar twinning</p> <p class="NoSpacing"><strong><span>M404 </span></strong><strong><span>Plagioclase feldspar, labradorite</span></strong><span> </span><br class="NoSpacing" /><strong>Labrador</strong><strong></strong><span> </span><br class="NoSpacing" />Dark grey, light where fragments are small due to cracking along cleavage<span> </span><br class="NoSpacing" />Schiller (blue iridescence), characteristic of labradorite<span> </span><br class="NoSpacing" />Very fine parallel striations due to lamellar twinning</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><span> </span><br /><a href="/p1acollections/exhibits/show/igneous-rocks/l101">L101 Granite</a><span> </span><br /><a href="/p1acollections/exhibits/show/igneous-rocks/l102">L102 Hornblende biotite granite</a><span> </span><br /><a href="/p1acollections/exhibits/show/igneous-rocks/l112">L112 Rhyolite</a><span> </span><br /><a href="/p1acollections/exhibits/show/igneous-rocks/l120">L120 Granodiorite</a><span> </span><br /><a href="/p1acollections/exhibits/show/igneous-rocks/l130">L130 Andesite, porphyritic (porphyrite)</a><span> </span><br /><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><span> </span><br /><a href="/p1acollections/exhibits/show/metamorphic-rocks/l504">L504 Garnet schist</a></p> </div> </div> <div class="element"> <h3>Advanced Notes</h3> <div class="element-text"> <p class="NoSpacing"><span>Plagioclase feldspar forms a continuous solid solution between the sodic endmember (albite, or Ab) and the calcic endmember (anorthite, or An). The series is sub-divided into albite (An_0-10), oligoclase (An_10-30) andesine (An_30-50), labradorite (An_50-70), bytownite (An_70-90) and anorthite (An_90-100).</span></p> </div> </div> <div class="element"> <h3>Mineral Name</h3> <div class="element-text">plagioclase<br />feldspar</div> </div> felsic igneous mafic metamorphic sedimentary https://wserv3.esc.cam.ac.uk/p1acollections/files/original/ac4a4b68b6b2ad4fef27b63699c1a3bf.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>Clinopyroxene (augite)</h2> Description An account of the resource <div class="element"> <h3>Formula</h3> <div class="element-text">(Ca,Mg,Fe²⁺,Fe³⁺,Ti,Al)₂[(Si,Al)₂O₆]</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</em><em><span> </span>system:</em><span> </span>monoclinic (+)</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 90°</span><span> </span><br class="NoSpacing" /><em><span>Hardness:</span></em><span> 5.5-6</span></p> </div> </div> <div class="element"> <h3>Optical Properties</h3> <div class="element-text"> <p class="NoSpacing"><em>Colour in plane polarised light:</em><span> </span>colourless, pale brown or pale grey<span> </span><br class="NoSpacing" /><em>Pleochroism:</em><span> </span>variable weak to moderate<span> </span><br class="NoSpacing" /><em>Relief:</em><span> </span>moderate<span> </span><br class="NoSpacing" /><em>Birefringence:</em><span> </span>0.018-0.033; 1^st<span> </span>order pink to 2^nd<span> </span>order orange<span> </span><br class="NoSpacing" /><em>Extinction:</em><span> </span>inclined<span> </span><em><br />Twinning:</em><span> </span>simple, common</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/l161">L161 Basalt, amygdaloidal</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"> <p class="NoSpacing"><span>Clinopyroxene contains calcium. It encompasses a range of solid solutions from (Mg,Fe)₂[Si₂O₆] to Ca(Mg,Fe)[Si₂O₆]. The physical and optical properties detailed above refer to augite, a clinopyroxene common in mafic igneous rocks.</span></p> </div> </div> <div class="element"> <h3>Mineral Name</h3> <div class="element-text">clinopyroxene<br />augite</div> </div> mafic ultramafic 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 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 https://wserv3.esc.cam.ac.uk/p1acollections/files/original/6ee5b4daa895a80c4f5d1219f546fd1f.jpg ec992c8fa5fc180cef9aa183c5fccb0b https://wserv3.esc.cam.ac.uk/p1acollections/files/original/f04b282ccc316fc1d49d4170730b5892.jpg 7759e3afb21758ccf4ccadb89eb40ce9 https://wserv3.esc.cam.ac.uk/p1acollections/files/original/d5a2b07e623f5f5b39a9506ee7ac050f.jpg 41972d8ec488fd6c039ae81709eaf2e3 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><strong>L161<br /></strong></h2> <h2>Basalt, amygdaloidal</h2> Subject The topic of the resource <h3>Specimen Age</h3> <div class="element-text"> <p>Cenozoic</p> <h3>Location</h3> <div class="element-text"> <p>Lava, Skye</p> </div> </div> Description An account of the resource <div class="element-set"> <div class="element"> <div class="element-text"> <div class="element"> <div class="element-text five columns omega"> <div class="element-text"> <div class="element-text"> <div class="element"> <div class="element-text five columns omega"> <div class="element-text"> <div class="element-text"></div> </div> </div> </div> <div class="element"> <div class="element-text five columns omega"> <div class="element-set"> <div class="element"> <div class="element-text"> <h3>Hand Specimen</h3> </div> </div> </div> <div class="element-set"> <div class="element"> <div class="element-text"> <p>Fine-grained, greenish black rock comprising dark and white minerals.<span> </span><br />Contains<span> </span><a href="/p1acollections/items/show/172">amygdales</a>, mostly white, though some have black cores.</p> </div> </div> <div class="element"> <h3>Thin-section</h3> <div class="element-text"> <p>Fine-grained plagioclase<span> </span><a href="/p1acollections/items/show/215">laths</a><span> </span>and irregular clinopyroxene (augite) grains, replaced with calcite. Many of the plagioclase laths have been almost entirely altered.</p> <p>The amygdales are filled with<span> </span><span>zeolite</span>, growing in spherulitic and radiate patterns. Many have rims of calcite and fine-grained chlorite.</p> <p>Some vein material -<span> </span><a href="/p1acollections/items/show/203">granular</a><span> </span>quartz with<span> </span><a href="/p1acollections/items/show/257">sutured contacts</a>.</p> </div> </div> <div class="element"> <h3>Rock History</h3> <div class="element-text"> <p>Fine-grained → rapid,<span> </span><a href="/p1acollections/items/show/191">extrusive</a><span> </span>crystallisation.<span> </span><br />Gas bubbles trapped within lava produced<span> </span><a href="/p1acollections/items/show/264">vesicles</a>.<span> </span><br />Circulation of fluids → precipitation of zeolite within the vesicles.</p> </div> </div> <div class="element"> <h3>Advanced Notes</h3> <div class="element-text"> <p><span>Zeolites</span><span> </span>are produced at low temperatures. They are commonly precipitated in basaltic volcanic piles.</p> </div> </div> <div class="element"> <h3>Rock Name</h3> <div class="element-text">amygdaloidal basalt</div> </div> </div> </div> </div> </div> </div> </div> </div> </div> </div> </div> alteration extrusive mafic https://wserv3.esc.cam.ac.uk/p1acollections/files/original/8c4e9f36beb5bdf91c3074408b01ccb0.jpg 8d6162debca1ae51b62f6d3fa743c662 https://wserv3.esc.cam.ac.uk/p1acollections/files/original/f5b37535e34701668500f4bbe72bc177.jpg 89547f12b6956f7a89eb9343ae4b2e08 https://wserv3.esc.cam.ac.uk/p1acollections/files/original/7e2698eb1f83d2a13be41526939fc1c4.jpg 92e7719401b0ee848bad92f1f3c3f023 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><strong>L141<br /></strong></h2> <h2>Gabbro</h2> Description An account of the resource <div class="element"> <div class="element"> <div class="element-text five columns omega"> <div class="element"> <h3>Hand Specimen</h3> <div class="element-text">Very dark grey, coarse-grained rock, typical grain size 1-2 mm.<span> </span><br />Main mineral phases are black clinopyroxene, greenish olivine and pale grey feldspar. The rock is cross-cut by a small number of hairline white veins.</div> </div> <div class="element"> <h3>Thin-section</h3> <div class="element-text"> <p>Plagioclase feldspar<span> </span><br />-<span> </span><a href="/p1acollections/items/show/258">Tabular</a><span> </span>phenocrysts making-up ~50% of the rock. Characteristic<span> </span><a href="/p1acollections/items/show/169">lamellar twinning</a>. Some are<span> </span><a href="/p1acollections/items/show/267">zoned</a>.</p> <p>Olivine<span> </span><br />-<span> </span><a href="/p1acollections/items/show/236">Phenocrysts</a><span> </span>have been extensively altered, rendering them almost unrecognisable. The olivine has decomposed to magnetite and serpentine. Relict olivine grains display characteristic curving cracks and<span> </span><a href="/p1acollections/items/show/189">euhedral</a><span> </span><a href="/p1acollections/items/show/206">form</a>.</p> <p>Clinopyroxene (augite)<span> </span><br />-<span> </span><a href="/p1acollections/items/show/211">Interstitial</a><span> </span>grains making-up ~35% of the rock.<span> </span><a href="/p1acollections/items/show/241">Poikilitic</a><span> </span>texture. Inclined<span> </span><a href="/p1acollections/items/show/190">extinction</a>. Interference colours from first order pink to second order orange. Pale grey under plane polarised light. Some simple twinning.</p> <p>Accessory minerals<span> </span><br />- Opaque, interstitial, probably magnetite.</p> </div> </div> <div class="element"> <h3>Rock History</h3> <div class="element-text"> <p>Coarse grained → slowly cooled,<span> </span><a href="/p1acollections/items/show/212">intrusive</a>.<span> </span><br />Hydrothermal<span> </span><a href="/p1acollections/items/show/170">alteration</a><span> </span>of olivine after crystallisation of the rock.</p> </div> </div> <div class="element"> <h3>Rock Name</h3> <div class="element-text">gabbro</div> </div> </div> </div> </div> alteration interstitial intrusive mafic phenocryst