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geode
geode , hollow, globular rock nodule ranging in diameter from 1 to 12 in. (2.54–30.5 cm) or more. Most geodes are partly filled with mineral matter; they have a thin layer of chalcedony ( "wavy" quartz) covering an inner lining of inward-projecting crystals. These spectacular crystals, generally quartz or, less often, calcite, make geodes highly prized by collectors. Geodes are formed in a cavity such as might be found inside a fossil shell buried in sediment. At the beginning, this cavity is probably filled with a concentrated salt solution. The first step in the creation of a geode is the formation along the inner cavity wall of a layer of gelatinous silica, which will eventually be transformed into the chalcedony layer. As the water surrounding the layer becomes less salty, osmosis induces migration of fluids into the cavity. This results in a buildup of pressure, causing the cavity to expand until the water inside and outside is equally salty. When the silica gel dehydrates, crystallizes to form chalcedony, and cracks, mineral-bearing water enters to slowly deposit the inward-projecting crystals. A geode measuring 26 ft (8 m) long and 6 ft (1.8 m) across was found in an old silver mine near Almería, NE Spain, in 2000. See also concretion . |
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"geode." The Columbia Encyclopedia, 6th ed.. 2011. Encyclopedia.com. 26 May. 2012 <http://www.encyclopedia.com>. "geode." The Columbia Encyclopedia, 6th ed.. 2011. Encyclopedia.com. (May 26, 2012). http://www.encyclopedia.com/doc/1E1-geode.html "geode." The Columbia Encyclopedia, 6th ed.. 2011. Retrieved May 26, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1E1-geode.html |
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geode
ge·ode / ˈjēōd/ • n. a small cavity in rock lined with crystals or other mineral matter. ∎ a rock containing such a cavity. DERIVATIVES: ge·od·ic / jēˈädik/ adj. |
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"geode." The Oxford Pocket Dictionary of Current English. 2009. Encyclopedia.com. 26 May. 2012 <http://www.encyclopedia.com>. "geode." The Oxford Pocket Dictionary of Current English. 2009. Encyclopedia.com. (May 26, 2012). http://www.encyclopedia.com/doc/1O999-geode.html "geode." The Oxford Pocket Dictionary of Current English. 2009. Retrieved May 26, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O999-geode.html |
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geode
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AILSA ALLABY and MICHAEL ALLABY. "geode." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. 26 May. 2012 <http://www.encyclopedia.com>. AILSA ALLABY and MICHAEL ALLABY. "geode." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. (May 26, 2012). http://www.encyclopedia.com/doc/1O13-geode.html AILSA ALLABY and MICHAEL ALLABY. "geode." A Dictionary of Earth Sciences. 1999. Retrieved May 26, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O13-geode.html |
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geode
geode. Piece of rock having a druse, or cavity lined with crystals, or a rounded hollow iron-stone nodule used e.g. in rock-rash facings.
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JAMES STEVENS CURL. "geode." A Dictionary of Architecture and Landscape Architecture. 2000. Encyclopedia.com. 26 May. 2012 <http://www.encyclopedia.com>. JAMES STEVENS CURL. "geode." A Dictionary of Architecture and Landscape Architecture. 2000. Encyclopedia.com. (May 26, 2012). http://www.encyclopedia.com/doc/1O1-geode.html JAMES STEVENS CURL. "geode." A Dictionary of Architecture and Landscape Architecture. 2000. Retrieved May 26, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O1-geode.html |
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geode
geode XVII. — L. geōdēs — Gr. geṓdēs earthy. f. gê earth.
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T. F. HOAD. "geode." The Concise Oxford Dictionary of English Etymology. 1996. Encyclopedia.com. 26 May. 2012 <http://www.encyclopedia.com>. T. F. HOAD. "geode." The Concise Oxford Dictionary of English Etymology. 1996. Encyclopedia.com. (May 26, 2012). http://www.encyclopedia.com/doc/1O27-geode.html T. F. HOAD. "geode." The Concise Oxford Dictionary of English Etymology. 1996. Retrieved May 26, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O27-geode.html |
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geode
geode
•abode, bestrode, bode, code, commode, corrode, download, encode, erode, explode, forebode, goad, implode, load, lode, middle-of-the-road, mode, node, ode, offload, outrode, road, rode, sarod, Spode, strode, toad, upload, woad
•geode
•diode, triode
•barcode • zip code • unhallowed
•carload • cartload • payload
•trainload • caseload • freeload
•peakload • shipload • coachload
•boatload • truckload • wagonload
•workload • anode • internode
•epode • antipode • electrode
•railroad
•byroad, highroad
•rhapsode • episode • cestode
•nematode, trematode
•cathode
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"geode." Oxford Dictionary of Rhymes. 2007. Encyclopedia.com. 26 May. 2012 <http://www.encyclopedia.com>. "geode." Oxford Dictionary of Rhymes. 2007. Encyclopedia.com. (May 26, 2012). http://www.encyclopedia.com/doc/1O233-geode.html "geode." Oxford Dictionary of Rhymes. 2007. Retrieved May 26, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O233-geode.html |
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