1 10 1 https://wserv3.esc.cam.ac.uk/p1acollections/files/original/852a77355d6e4e7f6cf8052de0bf7a9d.jpg 3418fba1e4453736b6dbd51d55fd9583 https://wserv3.esc.cam.ac.uk/p1acollections/files/original/aab79550a27397bff8be8a5cb67ef43f.jpg f5f51d065ee3cc8e993e930077cbd5fc https://wserv3.esc.cam.ac.uk/p1acollections/files/original/1c200ce8cf23f154e881c3c62ad865c8.jpg 25a8c42f179836492f49a6fdb0bcbb5f https://wserv3.esc.cam.ac.uk/p1acollections/files/original/f3204ba875eb0b5fb7aaffafd6e91261.jpg 6a3a28ccf49c7653bc57780b5eacdd11 https://wserv3.esc.cam.ac.uk/p1acollections/files/original/57c910796611238dbf565e32ca5fc702.jpg d53f7084c610e651bdaf2389f9297e28 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>L162<br /></strong></h2> <h2>Basalt, porphyritic</h2> Subject The topic of the resource <h3>Specimen Age</h3> <div class="element-text"> <p>Carboniferous</p> <h3>Location</h3> <div class="element-text"> <p>Volcanic neck, Lion's Haunch, Arthur's Seat, Edinburgh</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"> <div class="element-text five columns omega"></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>Black,<span> </span><a href="https://wserv3.esc.cam.ac.uk/p1acollections/items/show/244">porphyritic</a><span> </span>rock comprising black clinopyroxene, grey feldspar and greenish olivine<span> </span><a href="https://wserv3.esc.cam.ac.uk/p1acollections/items/show/236">phenocrysts</a>, in a fine-grained<span> </span><a href="https://wserv3.esc.cam.ac.uk/p1acollections/items/show/205">groundmass</a>.</p> </div> </div> <div class="element"> <h3>Thin-section</h3> <div class="element-text"> <p>Plagioclase feldspar<span> </span><br />- Phenocrysts 1-4mm long, with a euhedral,<span> </span><a href="https://wserv3.esc.cam.ac.uk/p1acollections/items/show/258">tabular</a><span> </span><a href="https://wserv3.esc.cam.ac.uk/p1acollections/items/show/206">form</a>. Randomly orientated. Characteristic<span> </span><a href="https://wserv3.esc.cam.ac.uk/p1acollections/items/show/169">lamellar twinning</a>. Some are<span> </span><a href="https://wserv3.esc.cam.ac.uk/p1acollections/items/show/267">zoned</a>.<span> </span><a href="https://wserv3.esc.cam.ac.uk/p1acollections/items/show/210">Inclusions</a><span> </span>of magnetite, clinopyroxene and other minerals. Extensive<span> </span><a href="https://wserv3.esc.cam.ac.uk/p1acollections/items/show/170">alteration</a><span> </span>along abundant cracks.</p> <p>Clinopyroxene (augite)<span> </span><br />-<span> </span><a href="https://wserv3.esc.cam.ac.uk/p1acollections/items/show/189">Euhedral</a><span> </span>phenocrysts, 1-2 mm across. Moderate<span> </span><a href="https://wserv3.esc.cam.ac.uk/p1acollections/items/show/247">relief</a>, inclined<span> </span><a href="https://wserv3.esc.cam.ac.uk/p1acollections/items/show/190">extinction</a><span> </span>and first order pink to second order orange interference colours. Pale pink in thin-section. Some are<span> </span><a href="https://wserv3.esc.cam.ac.uk/p1acollections/items/show/267">zoned</a>.</p> <p>Olivine<span> </span><br />- Very few phenocrysts are fresh enough to be easily identifiable. These are colourless in plane polarised light, have moderate relief, and up to second order pink interference colours. No<span> </span><a href="https://wserv3.esc.cam.ac.uk/p1acollections/items/show/180">cleavage</a>.</p> <p>- 1st phase of alteration along cracks: The majority of the phenocrysts have been completely altered to greenish serpentine.</p> <p>- 2nd phase of alteration: orange brown mineral – probably the amphibole<span> </span><span>cummingtonite</span>. Characteristic curving cracks and the<span> </span><a href="https://wserv3.esc.cam.ac.uk/p1acollections/items/show/246">prismatic</a><span> </span>form of olivine are still visible.</p> <p>Groundmass<span> </span><br />- Fine-grained. Plagioclase feldspar needles, clinopyroxene, some olivine (mostly altered), and opaques, probably magnetite. Occasional calcite grain.</p> </div> </div> <div class="element"> <h3>Rock History</h3> <div class="element-text"> <p>Two stage cooling<span> </span><br />1. Phenocrysts grow slowly in a magma chamber.<span> </span><br />2. Fine-grained groundmass grew rapidly →<span> </span><a href="https://wserv3.esc.cam.ac.uk/p1acollections/items/show/191">extrusive</a>.<span> </span><br />Hydrothermal alteration, possibly as part of the<span> </span><a href="https://wserv3.esc.cam.ac.uk/p1acollections/items/show/266">volcanic</a><span> </span>pile.</p> </div> </div> <div class="element"> <h3>Advanced Notes</h3> <div class="element-text"><span>Cummingtonite</span><span> </span>is an amphibole. It is colourless to pale green in thin-section, has moderate relief and two cleavages which intersect at 56°.</div> </div> <div class="element"> <h3>Rock Name</h3> <div class="element-text">porphyritic basalt</div> </div> </div> </div> </div> </div> </div> </div> </div> </div> </div> </div> </div> </div> alteration extrusive volcanic