1 10 6 https://wserv3.esc.cam.ac.uk/p1acollections/files/original/20b9609f2cc656507a1fec2347d9df89.jpg fa472417a23e56ecbb9b556d05c4ffca https://wserv3.esc.cam.ac.uk/p1acollections/files/original/3404979c4792fa74731a7e04e3022017.jpg 599a58e88705064fd972b61f03d15f68 https://wserv3.esc.cam.ac.uk/p1acollections/files/original/65c206021f6f75651f1697f0cd29cf1d.jpg 06b1f7e0df480b95e954641fe6339f67 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>Mica, biotite</h2> Description An account of the resource <div class="element"> <h3>Formula</h3> <div class="element-text">K₂(Mg,Fe²⁺)_6-4(Fe³⁺,Al,Ti)_0-2[Si_6-5Al_2-3O₂₀](OH,F)₄</div> </div> <div class="element"> <h3>Structure</h3> <div class="element-text"> <p>Sheet silicate</p> </div> </div> <div class="element"> <h3>Crystal System</h3> <div class="element-text"> <p class="NoSpacing"><em><span>Crystal</span></em><em><span> system:</span></em><span> monoclinic (-)</span></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> brown or black</span><span> </span><br class="NoSpacing" /><em><span>Cleavage:</span></em><span> one, good</span><span> </span><br class="NoSpacing" /><em><span>Hardness:</span></em><span> 2-3</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> pale yellow, pale green, green or brown</span><span> </span><br /><em><span>Pleochroism:</span></em><span> strong</span><span> </span><br /><em><span>Relief:</span></em><span> low</span><span> </span><br /><em><span>Birefringence: </span></em><span>0.028-0.08; 2^nd order green-yellow to &gt;4^th order</span><span> </span><em><span><br />Extinction: </span></em><span>straight</span></p> </div> </div> <div class="element"> <h3>Mineral Specimens</h3> <div class="element-text"> <p class="NoSpacing"><strong><span>M303 </span></strong><strong><span>Mica, biotite</span></strong><span> </span><br class="NoSpacing" /><strong>Cornwall</strong><strong></strong><span> </span><br class="NoSpacing" />Large irregular biotite crystals in a feathery arrangement<span> </span><br class="NoSpacing" />Dark brown / black / golden<span> </span><br class="NoSpacing" />Metallic lustre<span> </span><br class="NoSpacing" />Platy habit due to the single perfect cleavage</p> <p class="NoSpacing"><strong><span>M304 </span></strong><strong><span>Mica, biotite</span></strong><span> </span><br class="NoSpacing" /><strong>Orlando</strong><strong>, Canada</strong><strong></strong><span> </span><br class="NoSpacing" />Irregular plates of biotite split along cleavage planes<span> </span><br class="NoSpacing" />One good cleavage<span> </span><br class="NoSpacing" />Brilliant metallic lustre</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/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/metamorphic-rocks/l504">L504 Garnet schist</a></p> </div> </div> <div class="element"> <h3>Mineral Name</h3> <div class="element-text">mica<br />biotite</div> </div> basal cleavage igneous metapelite https://wserv3.esc.cam.ac.uk/p1acollections/files/original/f45fcf901e391b706d58c5a76ce9e0f7.jpg 0b887bd5e1ae09a04261e9bb9af69078 https://wserv3.esc.cam.ac.uk/p1acollections/files/original/daa51ed8284e2f268043c893ed2835dc.jpg 1c07f39572ce1f39720e395b2d729c83 https://wserv3.esc.cam.ac.uk/p1acollections/files/original/f85892ba7ce86764f8dafc18adab40a6.jpg e9b02c931f4847fb3d65e56480cc42d2 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>Mica, muscovite</h2> Description An account of the resource <div class="element"> <h3>Formula</h3> <div class="element-text">K₂Al₄[Si₆Al₂O₂₀](OH,F)₄</div> </div> <div class="element"> <h3>Structure</h3> <div class="element-text"> <p>Sheet silicate</p> </div> </div> <div class="element"> <h3>Crystal System</h3> <div class="element-text"> <p><em>Crystal 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> colourless</span><span> </span><br class="NoSpacing" /><em><span>Cleavage:</span></em><span> one, good</span><span> </span><br class="NoSpacing" /><em><span>Hardness:</span></em><span> 2.5-3</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:<span> </span></em>0.036-0.049; 2^nd<span> </span>order pink to 3^rdorder yellow<span> </span><br /><em>Extinction: </em>straight</p> </div> </div> <div class="element"> <h3>Mineral Specimens</h3> <div class="element-text"> <p class="NoSpacing"><strong><span>M301 </span></strong><strong><span>Mica, muscovite</span></strong><span> </span><br class="NoSpacing" /><strong>Lincoln County</strong><strong>, North Carolina</strong><strong></strong><span> </span><br class="NoSpacing" />Well-formed tabular crystals showing the pseudohexangonal symmetry<span> </span><br class="NoSpacing" />Colourless, mirror- like, metallic lustre<span> </span><br class="NoSpacing" />Platy, flaky habit<span> </span><br class="NoSpacing" />Soft</p> <p class="NoSpacing"><strong><span>M302 </span></strong><strong><span>Mica, muscovite</span>   <span> </span></strong><br class="NoSpacing" /><strong>Mysore</strong><strong>, India</strong><strong></strong><span> </span><br class="NoSpacing" />Plates of mica artificially cut to shape<span> </span><br class="NoSpacing" />Colourless<span> </span><br class="NoSpacing" />One perfect cleavage</p> </div> </div> <div class="element"> <h3>Rock Specimens</h3> <div class="element-text"> <p><a href="/p1acollections/exhibits/show/igneous-rocks/l110">L110 Rhyolite, porphyritic (quartz porphyry)</a><span> </span><br /><a href="/p1acollections/exhibits/show/volcaniclastic-rocks/l201">L201 Tuff</a><span> </span><br /><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">mica<br />muscovite</div> </div> basal cleavage igneous metapelite 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/74710dbf85be2a6e9e238ba537ef6ad4.jpg 28595880e272b17b8a23671cdc97d677 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>Garnet</h2> Description An account of the resource <div class="element"> <h3>Formula</h3> <div class="element-text">(Mg,Fe,Ca)₃Al₂Si₃O₁₂</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>cubic</p> </div> </div> <div class="element"> <h3>Physical Properties</h3> <div class="element-text"> <p><em>Colour in hand specimen:</em><span> </span>typically red<br /><em>Cleavage:</em><span> </span>none<br /><em>Hardness:</em><span> </span>6-7.5</p> </div> </div> <div class="element"> <h3>Optical Properties</h3> <div class="element-text"> <p><em>Colour in plane polarised light:</em><span> </span>colourless, pale pink<span> </span><br /><em>Pleochroism:</em><span> </span>none<br /><em>Relief:</em><span> </span>high<br />Isotropic</p> </div> </div> <div class="element"> <h3>Mineral Specimens</h3> <div class="element-text"> <p><span><strong>M130 Garnet schist</strong></span><br /><strong>Portsoy, Banffshire</strong><br />Euhedral porphyroblasts of dark-red garnet, with quartz, mica and other minerals in a medium-grade metamorphic rock.</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>Advanced Notes</h3> <div class="element-text"> <p>The garnet group encompasses a wide range of compositions, and consequently a range of optical and physical properties. The properties detailed above are typical of pyrope (Mg₃Al₂Si₃O₁₂), almandine (Fe²⁺₃Al₂Si₃O₁₂) and grossular (Ca₃Al₂Si₃O₁₂).</p> </div> </div> <div class="element"> <h3>Mineral Name</h3> <div class="element-text">garnet</div> </div> metamorphism metapelite 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 https://wserv3.esc.cam.ac.uk/p1acollections/files/original/f6e898cd01802fb7acdebb33ce327862.jpg 63ab96468652d4ce048e01dc652b190f https://wserv3.esc.cam.ac.uk/p1acollections/files/original/dded11a8e088fb9744260bddcb9b5015.jpg cbf87a0795d18f9b11a03ab73acf8183 https://wserv3.esc.cam.ac.uk/p1acollections/files/original/0a7fda527a98690dcee575c19b33a611.jpg 6edb633111e026da117eb2b2b9d0ee41 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>L500<br /></strong></h2> <h2>Slate</h2> Subject The topic of the resource <h3>Age</h3> <div class="element-text"> <p>Lower Cambrian</p> <h3>Location</h3> <div class="element-text"> <p>Llanberis, North Wales</p> </div> </div> Description An account of the resource <div class="element"> <h3>Hand Specimen</h3> <div class="element-text"> <p>Very fine-grained rock with a prominent, well-developed<span> </span><a href="/p1acollections/items/show/180">cleavage</a>. The dark red-purple colour is due to<span> </span><span>iron-staining</span>. The light green smudge is a<span> </span><span>reduction spot</span>.</p> </div> </div> <div class="element"> <h3>Thin-section</h3> <div class="element-text"> <p>Mud size grains.<br />Mainly indistinguishable clay minerals.<br />Some quartz, muscovite, opaques.</p> </div> </div> <div class="element"> <h3>Rock History</h3> <div class="element-text"> <p>The protolith of this rock was a pelite (mudstone). Under low-grade, regional metamorphic conditions, crystals within the pelite were aligned, producing the slaty cleavage.</p> </div> </div> <div class="element"> <h3>Advanced Notes</h3> <div class="element-text"> <p><span>Iron staining</span><span> </span><br />Hematite(Fe₂O₃) → red (blood-red, cherry-red, brown-red) iron-staining<span> </span><br />Limonite (FeO(OH)·nH₂O) → yellow or brown iron-staining<span> </span><br />The red-purple colour of this rock is probably produced by hematite.</p> <p><span>Reduction spot</span><span> </span><br />The dark red-purple of the majority of this rock is due to the presence of iron in the 3+ oxidation state (Fe³⁺). The light green colour of the reduction spot is instead due to the presence of iron in the 2+ oxidation state (Fe²⁺). Hence,<span> </span><em>reduction</em><span> </span>of the iron ions from Fe³⁺<span> </span>to Fe²⁺<span> </span>has taken place in the reduction spot.</p> </div> </div> <div class="element"></div> <div class="element"></div> <div class="element"> <h3>Rock Name</h3> <div class="element-text">slate</div> </div> Date A point or period of time associated with an event in the lifecycle of the resource Lower Cambrian metapelite reduction