27
10
264
-
https://wserv3.esc.cam.ac.uk/p1acollections/files/original/e3160631658548f9f2dc6e1becea70da.jpg
d95ec5a176a934d2c3e57276e230693c
https://wserv3.esc.cam.ac.uk/p1acollections/files/original/e2173d02d96267ba32160e6fdf7413e7.jpg
6064d39c4c259244a0f9ee941313b06b
https://wserv3.esc.cam.ac.uk/p1acollections/files/original/01845924716bedfe0fd182d669f227cd.jpg
29966d5660a6a3fe8f268bf574236f17
https://wserv3.esc.cam.ac.uk/p1acollections/files/original/16d925108b74372b95b4fdde50676900.jpg
5258ac41a282f9310c3fe1c4115cc800
https://wserv3.esc.cam.ac.uk/p1acollections/files/original/f8b28219498294d826754ab3542fb00f.jpg
c99a49a3bc0d2fc2234806df01cd66c1
https://wserv3.esc.cam.ac.uk/p1acollections/files/original/ac59d17b2a65340795a83853876e0422.jpg
27acfdf84cb9a638c01a6ee7daebba0e
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>L102<br /></strong></h2>
<h2>Hornblende biotite granite</h2>
Subject
The topic of the resource
<h3>Age</h3>
<div class="element-text">
<p>Caledonian, Devonian</p>
<h3>Location</h3>
<div class="element-text">
<p>Glencoe</p>
</div>
</div>
Description
An account of the resource
<div class="element-set">
<div class="element">
<div class="element-text">
<div class="element-set">
<div class="element">
<div class="element-text">
<h3><span style="font-size:14px;">Hand Specimen</span></h3>
</div>
</div>
</div>
<div class="element-set">
<div class="element">
<div class="element-text">
<p>Medium to coarse-grained rock with a<span> </span><a href="/p1acollections/items/show/203">granular</a><span> </span>texture.<span> </span><br />White feldspar<span> </span><a href="/p1acollections/items/show/215">laths</a><span> </span>2-4 mm long are clearly visible.<span> </span><br />Other phases: pink feldspar, black biotite mica, black hornblende amphibole and pale grey quartz. These grains are more<span> </span><a href="/p1acollections/items/show/188">equant</a>, typically 1-2 mm across.<span> </span><br />Biotite may be distinguished from hornblende by its flaky<span> </span><a href="/p1acollections/items/show/206">habit</a><span> </span>and one good<span> </span><a href="/p1acollections/items/show/180">cleavage</a>. It is shinier than hornblende.</p>
</div>
</div>
<div class="element">
<h3>Thin-section</h3>
<div class="element-text">
<p>Plagioclase feldspar<span> </span><br />- The larger laths (2-4 mm long) are strongly<span> </span><a href="/p1acollections/items/show/267">zoned</a>. The cores of these laths, which display clear<span> </span><a href="/p1acollections/items/show/169">lamellar twinning</a>, have been<span> </span><a href="/p1acollections/items/show/232">overgrown</a><span> </span>by rims of more feldspar. Some<span> </span><a href="/p1acollections/items/show/170">alteration</a><span> </span>to white mica.</p>
<p>Biotite mica<span> </span><br />- Grains typically 1 mm across. Strongly pleochroic in reddish brown and pale straw. Often associated with small grains of an opaque accessory mineral, probably magnetite.</p>
Quartz<span> </span><br />- Grains are 1-2 mm across,<span> </span><a href="/p1acollections/items/show/173">anhedral</a>, and display<span> </span><a href="/p1acollections/items/show/263">undulose extinction</a>.
<p>Alkali feldspar<span> </span><br />- Anhedral grains up to 5mm long. Some alteration to white mica. Some grains display a<span> </span><a href="/p1acollections/items/show/228">microperthite texture</a>.</p>
<p>Hornblende amphibole<span> </span><br />- Pale green, anhedral. Grains appear to have been “eaten away”, reducing their<span> </span><a href="/p1acollections/items/show/246">prismatic</a><span> </span>form (diamond) to a ragged anhedral<span> </span><a href="/p1acollections/items/show/206">form</a>. Amphiboles have two cleavage planes which intersect at 56°.</p>
</div>
</div>
<div class="element">
<h3>Rock History</h3>
<div class="element-text">This coarse-grained rock must have cooled slowly as part of an intrusion.<br /><br />Its granitic composition (essential quartz and feldspar) indicates that it was produced in a continental setting.<br /><br />Strongly zoned plagioclase crystals and “eaten away” appearance of the hornblende could be due to a change in the composition of the liquid from which the phases crystallised; perhaps due to magma mixing or degassing of volatiles from the magma.<span> </span><br /><br />Presence of hornblende and biotite indicate that this is a wet granite, probably from a subduction zone.<br /><br />Hydrothermal alteration of feldspars to white mica.</div>
</div>
<div class="element">
<h3>Advanced Notes</h3>
<div class="element-text">
<p>This rock is classified as an<span> </span><span>adamellite</span><span> </span>because it contains roughly equal proportions of alkali feldspar and plagioclase feldspar, with additional quartz and biotite.</p>
</div>
</div>
<div class="element">
<h3>Rock Name</h3>
<div class="element-text">
<p>hornblende biotite granite<br />adamellite</p>
</div>
</div>
</div>
</div>
</div>
</div>
arc
biotite
coarse
granite
hornblende
subduction
-
https://wserv3.esc.cam.ac.uk/p1acollections/files/original/3fe81164e89cb8ce7ea324619c4a6800.jpg
4fba4b4108c529ccb7c8638941813e9f
https://wserv3.esc.cam.ac.uk/p1acollections/files/original/0f351e1be30ed9218d69f6e7be19c538.jpg
375d8c343a9559d5141db30e65426acc
https://wserv3.esc.cam.ac.uk/p1acollections/files/original/4a7d0ec7c3d779cc3bb42f7856e405ef.jpg
7efb2834c8830784edcdb8e129cd4848
https://wserv3.esc.cam.ac.uk/p1acollections/files/original/24f4a832b846ebe79e388cd619f863af.jpg
2c40579ff6e440ee59364245fffabef6
https://wserv3.esc.cam.ac.uk/p1acollections/files/original/a510299fa5a7c375958cbe1f972da092.jpg
89e9195c406cb49ad3d667bce0a238f9
https://wserv3.esc.cam.ac.uk/p1acollections/files/original/28f8f145e2f3fbe758a59b9a674fec61.jpg
e63f4971fc2cbfa3a255b7dd89f6a6d7
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>L340<br /></strong></h2>
<h2>Mudstone</h2>
Subject
The topic of the resource
<h3>Age</h3>
<div class="element-text">Cambrian<br /><h3>Location</h3>
<div class="element-text">Solva, South Wales</div>
</div>
Description
An account of the resource
<div class="element">
<h3>Hand Specimen</h3>
<div class="element-text">Superficially specimens “a” and “b” look very different due to their colours. L340a is pale grey, while L340b is dark purple-red. The colour of L340b indicates that it is ferruginous, containing significant quantities of iron oxide.<br /><br />These are mudstones, made up of clay and/or silt sized grains.<span> </span><br />Contain some glinting mica flakes.<span> </span><br />Do not react with acid, so do not contain significant carbonate.</div>
</div>
<div class="element">
<h3>Thin-section</h3>
<div class="element-text">
<p>L340a<span> </span><br />- Homogeneous texture apart from one hairline quartz vein. Mainly mud sized grains too small to be distinguished, but probably clay minerals. Some silt sized grains of quartz, plagioclase and white mica. Patches of minor red-brown<span> </span><span>iron staining</span>.</p>
<p>L340b<span> </span><br />- Hold up to light to see discontinuous, wavy laminations. Mud sized grains of quartz, feldspar, white mica and opaque minerals. Red<span> </span><span>iron-staining</span>.</p>
</div>
</div>
<div class="element">
<h3>Rock History</h3>
<div class="element-text">The dark purple-red of L340b indicates an oxidising environment during diagenesis, while the grey colour of L340a indicates a reducing environment.<br /><br />Non-marine environments are more likely to be oxidising than marine environments where organic matter tends to promote a reducing environment during diagenesis. Reducing environments are associated with grey, black or greenish rocks.</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</p>
<p>The red / red-brown colours of these rocks is probably produced by hematite.</p>
</div>
</div>
<div class="element"></div>
<div class="element"></div>
<div class="element">
<h3>Rock Name</h3>
<div class="element-text">mudstone</div>
</div>
oxidation
reduction
-
https://wserv3.esc.cam.ac.uk/p1acollections/files/original/744797d8340f3fb3bb5223f8d6e813df.jpg
2216573b7943b4d2108e89ba7c1ae3ee
https://wserv3.esc.cam.ac.uk/p1acollections/files/original/6ca84b87271026626b96c159bfd42604.jpg
5fed78d37132afb7111530b3f05d4631
https://wserv3.esc.cam.ac.uk/p1acollections/files/original/6e5325c5d9551839979a6bc06bdf7a19.jpg
d843ba39bcd4aa3e3a92b6b8306412a7
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>L101<br /></strong></h2>
<h2>Granite</h2>
Subject
The topic of the resource
<h3><strong>Age</strong></h3>
Caledonian, Devonian<br /><br /><h3><strong> Location</strong></h3>
Shap Fell, Cumbria
Description
An account of the resource
<div class="element-set">
<div class="element">
<div class="element-text">
<h3 class="element-set"><strong>Hand</strong> Specimen</h3>
<div class="element-set">
<div class="element">
<div class="element-text">
<p>Coarse-grained,<span> </span><a href="/p1acollections/items/show/244">porphyritic</a><span> </span>texture.<span> </span><br /><a href="/p1acollections/items/show/236">Phenocrysts</a><span> </span>of pink feldspar, 10-30 mm long,<span> </span><a href="/p1acollections/items/show/258">tabular</a>, display clear<span> </span><a href="/p1acollections/items/show/180">cleavage</a> planes.<span> </span><br /><a href="/p1acollections/search?query=groundmass&query_type=keyword&record_types%5B%5D=Item&record_types%5B%5D=File&record_types%5B%5D=Collection&record_types%5B%5D=Exhibit&record_types%5B%5D=ExhibitPage&record_types%5B%5D=SimplePagesPage&submit_search=Search">Groundmass</a><span> </span>of coarse-grained white feldspar, pink feldspar, quartz and biotite.<span> </span><br />Quartz grains are<span> </span><a href="/p1acollections/items/show/173">anhedral</a><span> </span>and display their characteristic<span> </span><a href="/p1acollections/items/show/182">conchoidal fracture</a><span> </span>and<span> </span><a href="/p1acollections/items/show/265">vitreous lustre</a>.</p>
<div class="element">
<h3>Thin-section</h3>
<div class="element-text">
<p>Alkali feldspar (orthoclase)<span> </span><br />- Pink phenocrysts up to ~10 mm long, relatively fresh (unaltered).</p>
<p>Groundmass<span> </span><br />- Feldspar (both plagioclase and alkali) grains 1-4mm long, mainly<span> </span><a href="/p1acollections/items/show/256">subhedral</a>, though some are quite<span> </span><a href="/p1acollections/items/show/215">lath</a><span> </span>shaped. Partially altered. The plagioclase grains display their characteristic<span> </span><a href="/p1acollections/items/show/169">lamellar twinning</a>.<span> </span><br />- Biotite grains (0.5-2 mm) with subhedral to anhedral<span> </span><a href="/p1acollections/items/show/206">form</a>. Grains have ragged edges and are partially altered to chlorite, mainly along<span> </span><a href="/p1acollections/items/show/180">cleavage</a><span> </span>planes.<span> </span><br />- Quartz grains (typically 2-5 mm) contain lots of tiny<span> </span><a href="/p1acollections/items/show/210">inclusions</a><span> </span>and display<span> </span><a href="/p1acollections/items/show/263">undulose extinction</a>.</p>
<p>Accessory minerals<span> </span><br />- Sphene<span> </span><br />- Apatite<span> </span><br />- Opaque mineral</p>
</div>
</div>
<div class="element">
<h3>Rock History</h3>
<div class="element-text">
<p>Porphyritic texture means this rock underwent two stages of cooling; phenocrysts crystallised first followed by the groundmass. The groundmass is coarse-grained, and must have crystallised slowly as part of an intrusion.</p>
<p>Plagioclase and alkali feldspar both occur in this rock, indicating that it formed at high pressures.</p>
<p>Granitic composition (essential quartz and feldspar) indicates that it was produced in a continental setting. Late-stage<span> </span><a href="/p1acollections/items/show/170">alteration</a>.</p>
</div>
</div>
<div class="element">
<h3>Advanced Notes</h3>
<div class="element-text">
<p>This rock is classified as an<span> </span><span>adamellite</span><span> </span>because it contains roughly equal proportions of alkali feldspar and plagioclase feldspar, as well as biotite and quartz.</p>
</div>
</div>
<div class="element">
<h3>Rock Name</h3>
<div class="element-text">
<p>granite<br />adamellite</p>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
alkali
alteration
feldspar
-
https://wserv3.esc.cam.ac.uk/p1acollections/files/original/f05e63c01d867dcb78bad17121fd1d31.jpg
2d73462e69c78971d66f92dd5d6e622b
https://wserv3.esc.cam.ac.uk/p1acollections/files/original/8a6e1a596d0d3bc7ae44e61aab691d56.jpg
84814d5a6509f76521cd808580d14224
https://wserv3.esc.cam.ac.uk/p1acollections/files/original/4b619fdf5cbd3e05bf7ad22b3494cef3.jpg
bdc304f5ffbdb6cb553489a47568c9ca
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>L100<br /></strong></h2>
<h2>Alkali granite</h2>
Subject
The topic of the resource
<h3>Specimen Age</h3>
<p>Variscan , Permo-Carboniferous</p>
<h3></h3>
Description
An account of the resource
<h3><span style="font-size:14px;">Hand Specimen</span></h3>
<div class="element-set">
<div class="element">
<div class="element-text">
<p>This rock has a<span> </span><a href="/p1acollections/items/show/244">porphyritic</a><span> </span>texture.<span> </span><a href="/p1acollections/items/show/236">Phenocrysts</a><span> </span>of white feldspar up to 30mm long are surrounded by a coarse<span> </span><a href="/p1acollections/items/show/205">groundmass</a><span> </span>of quartz, biotite and white feldspar.</p>
</div>
</div>
<div class="element">
<h3>Thin-section</h3>
<div class="element-text">
<p>Alkali feldspar (orthoclase)<span> </span><br />- Grains typically 2-4mm long,<span> </span><a href="/p1acollections/items/show/256">subhedral</a><span> </span>to<span> </span><a href="/p1acollections/items/show/173">anhedral</a>, dirty looking due to<span> </span><a href="/p1acollections/items/show/170">alteration</a>. Many display a<span> </span><a href="/p1acollections/items/show/228">microperthite texture</a>.</p>
<p>Plagioclase feldspar<span> </span><br />- Grains typically 1-4mm long, subhedral, characteristic<span> </span><a href="/p1acollections/items/show/169">lamellar twinning</a>. Many of the grains look “dirty” under plain polarised light, and have high<span> </span><a href="/p1acollections/items/show/177">birefringence</a><span> </span>speckles under cross-polarised light. They have been partially altered to white mica. Some grains are<span> </span><a href="/p1acollections/items/show/267">zoned</a>.</p>
<p>Quartz<span> </span><br />- Grains typically 1-4mm across, anhedral. They are characteristically clean and unaltered when compared with feldspar grains, but do contain many tiny<span> </span><a href="/p1acollections/items/show/210">inclusions</a>.</p>
<p>Biotite<span> </span><br />- Grains similar size as the rest of the<span> </span><a href="/p1acollections/items/show/205">groundmass</a>. Strongly<span> </span><a href="/p1acollections/items/show/239">pleochroic</a><span> </span>in pale straw and dark reddish brown. Speckled<span> </span><a href="/p1acollections/items/show/190">extinction</a>. Some sections show the one good<span> </span><a href="/p1acollections/items/show/180">cleavage</a><span> </span>of biotite. Small black blobs and circles are dotted all over the crystals. These are<span> </span><a href="/p1acollections/items/show/238">pleochroic haloes</a>, produced by zircons. Partially decomposed to chlorite.</p>
<p>Accessory minerals<span> </span><br />- Apatite<span> </span><br />- Small irregular grains of muscovite mica</p>
</div>
</div>
<div class="element">
<h3>Rock History</h3>
<div class="element-text">This is a coarse-grained rock, which must have cooled slowly as part of an intrusion. Its granitic composition (essential quartz and feldspar) indicates that it was produced in a continental setting.</div>
</div>
<div class="element">
<h3>Rock Name</h3>
<div class="element-text">alkali granite</div>
</div>
</div>
coarse
continental
felsic
inclusions