1 10 2 https://wserv3.esc.cam.ac.uk/p1acollections/files/original/a7df9ee4ba246ad0597901f02ce9248e.jpg c00e1ed63dab525439bafbcd93e404ad https://wserv3.esc.cam.ac.uk/p1acollections/files/original/a96297a90c4701546417a62762349b0c.jpg 10d02e1fb68349bfd8e84366835b2ca5 https://wserv3.esc.cam.ac.uk/p1acollections/files/original/5ef179694fabe2f138284ddd124cda39.jpg 712079ecee63ba6327aad3a1eddff03e 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>L521<br /></strong></h2> <h2>Quartzite</h2> Subject The topic of the resource <h3>Age</h3> <div class="element-text"> <p>Precambrian</p> <h3>Location</h3> <div class="element-text"> <p>Braemar, Aberdeenshire</p> </div> </div> Description An account of the resource <div class="element"> <div class="element"> <h3>Hand Specimen</h3> <div class="element-text"> <p>Buff coloured rock.<br />Almost pure quartz, which has been very well recrystallised.<br />Faint banding could be original bedding.</p> </div> </div> <div class="element"> <h3>Thin-section</h3> <div class="element-text"> <p>Fine to medium grained recrystallised 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>The sutured (ragged) grain boundaries and<span> </span><a href="/p1acollections/items/show/263">undulose extinction</a><span> </span>of the quartz grains indicate that this rock formed under relatively low temperature metamorphism. Had the rock been raised to higher temperatures perfect 120° grain boundaries would have formed, and the quartz would not be strained.</p> <p class="NoSpacing">Inserting the sensitive tint plate results in the vast majority of grains changing colour in the same way – most of the grains simultaneously display higher interference colours in one orientation, and lower interference colours in the other orientation. This strong<span> </span><a href="/p1acollections/items/show/192">fabric</a><span> </span>was produced by recrystallisation under directed stress, which caused all the grains to elongate in one direction. </p> </div> </div> <div class="element"></div> <div class="element"> <h3>Rock Name</h3> <div class="element-text">quartzite</div> </div> </div> banding foliation suture https://wserv3.esc.cam.ac.uk/p1acollections/files/original/57eb9d161e24081334fddcaa5522b630.jpg 98a53ec0911ccd3ce20f1096608dfa02 https://wserv3.esc.cam.ac.uk/p1acollections/files/original/e148827aaff78a32a6daf8c169fa2639.jpg 575620169218ba18643aec7f3f6febf5 https://wserv3.esc.cam.ac.uk/p1acollections/files/original/4441d696cc8b2928132fa37dbd6d8e4f.jpg e12bf8a89562af01f31acbf211a2e14f 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>L504</strong></h2> <h2>Garnet schist</h2> Subject The topic of the resource <h3>Age</h3> <div class="element-text"> <p>Pre-Devonian</p> <h3>Location</h3> <div class="element-text"> <p>Ny-Friesland, Spitsbergen</p> </div> </div> Description An account of the resource <div class="element"> <div class="element"> <h3>Hand Specimen</h3> <div class="element-text"> <p>Strongly developed planar<span> </span><a href="/p1acollections/items/show/192">fabric</a><span> </span>made up of<span> </span><a href="/p1acollections/items/show/237">platy</a><span> </span>biotite mica and muscovite mica grains and lenses of quartz grains. Fabric wraps around large,<span> </span><a href="/p1acollections/items/show/189">euhedral</a><span> </span>garnets, typically ~2mm across. Quartz, the most soluble mineral, has recrystallised at the corners of the “eyes”, in the pressure shadows of the garnets.</p> </div> </div> <div class="element"> <h3>Thin-section</h3> <div class="element-text"> <p>Bands of interlocking quartz grains and some feldspar (plagioclase and alkali,<span> </span><a href="/p1acollections/items/show/169">lamellar twinning</a><span> </span>and<span> </span><a href="/p1acollections/items/show/170">alteration</a>), alternate with bands composed of needles of biotite mica and muscovite mica, about 50:50.</p> <p>Quartz displays<span> </span><a href="/p1acollections/items/show/263">undulose extinction</a>, and being the most soluble mineral in this rock has recrystallised into the pressure shadows around the garnets.</p> <p>The fabric is interrupted by large<span> </span><a href="/p1acollections/items/show/189">euhedral</a><span> </span>garnet crystals. Characteristically the garnets are<span> </span><a href="/p1acollections/items/show/213">isotropic</a><span> </span>and have high<span> </span><a href="/p1acollections/items/show/247">relief</a>. They contain<span> </span><a href="/p1acollections/items/show/210">inclusions</a><span> </span>of quartz and mica.</p> <p>Accessory minerals:<span> </span><br />- chlorite<span> </span><br />-<span> </span><span>staurolite</span><span> </span><br />- tourmaline</p> </div> </div> <div class="element"> <h3>Rock History</h3> <div class="element-text"> <p>This schist contains large quantities of muscovite indicating that it had a pelitic protolith. This pelite was subjected to high pressures and temperatures during regional metamorphism, resulting in the crystallisation and alignment of metamorphic minerals.</p> <p>The<span> </span><a href="/p1acollections/items/show/198">foliation</a><span> </span>of this schist may be due to original compositional banding in the pelite; the quartz-rich layers having been sandy layers, while the mica-rich layers were muddy.</p> <p>Some evidence for post-metamorphic deformation: quartz displaying undulose extinction; micas are wrapped around the garnet grains.</p> <p>Tiny grains of chlorite found around the edges of the garnets indicate that some retrogradation has taken place. Chlorite is a common break-down product of garnets.</p> </div> </div> <div class="element"> <h3>Advanced Notes</h3> <div class="element-text"> <p>In thin-section<span> </span><span>staurolite</span><span> </span>is pale-golden in colour. It has high relief, and displays straight<span> </span><a href="/p1acollections/items/show/190">extinction</a><span> </span>and 1st order birefringence colours.</p> </div> </div> <div class="element"></div> <div class="element"></div> <div class="element"> <h3>Rock Name</h3> <div class="element-text">garnet schist</div> </div> </div> fabric foliation metapelite