1 10 1 https://wserv3.esc.cam.ac.uk/p1acollections/files/original/a208f3e1a4d5b13c2f81d3ec49b5b314.jpg a620047d874c5f7b4353192625ce8f7b https://wserv3.esc.cam.ac.uk/p1acollections/files/original/e237c8cfeee6fc635fea026faf549f99.jpg 081148ca95653367a2ff3adf38dcbe74 https://wserv3.esc.cam.ac.uk/p1acollections/files/original/b5fed400782b1050357184726a850f88.jpg 0f078f721ecc91609d3d3ea52ced6444 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>L370<br /></strong></h2> <h2>Chert, flint nodule</h2> Subject The topic of the resource <h3>Age</h3> <div class="element-text"> <p>Cretaceous</p> <h3>Location</h3> <div class="element-text"> <p>Upper Chalk, Cambridgeshire</p> </div> </div> Description An account of the resource <div class="element"> <div class="element"> <h3>Hand Specimen</h3> <div class="element-text"> <p>This rock is made up of<span> </span><a href="/p1acollections/items/show/184">cryptocrystalline</a><span> </span>silica (quartz), black to brown. Being made up of silica, it is hard and displays<span> </span><a href="/p1acollections/items/show/182">conchoidal fracture</a>.</p> <p>This is a flint nodule, which comes from a chalk bed – notice the thin shell of white chalk. Flints are irregular silica concretions characteristic of the upper Chalk.</p> </div> </div> <div class="element"> <h3>Thin-section</h3> <div class="element-text"> <p>Cryptocrystalline silica (quartz)<span> </span><br /><a href="/p1acollections/items/show/171">Amorphous</a>, not grains. Partially devitrified<span> </span><br />Uniform texture<span> </span><br />Rare larger quartz crystals</p> <p>Occasional elliptical strips of greater than average grain size probably represent cross-sections of shells now replaced by silica.</p> </div> </div> <div class="element"> <h3>Rock History</h3> <div class="element-text"> <p>Flint nodules are produced by the digenetic<span> </span><a href="/p1acollections/items/show/248">replacement</a><span> </span>of chalk. A silica gel, formed by the dissolution of sponge spicules, precipitates silica in nodules. Chert deposits are more common in organic-rich regions of the chalk, and there is a hypothesis that the silica precipitates in burrows.</p> </div> </div> <div class="element"></div> <div class="element"></div> <div class="element"> <h3>Rock Name</h3> <div class="element-text">chert<br />flint nodule</div> </div> </div> diagenesis sponge