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344:. The cavity, which measured 8.0 by 1.8 by 1.7 metres (26.2 ft × 5.9 ft × 5.6 ft), was, at the time, the largest crystal cave ever found. Following its discovery, the entrance to the cave was blocked by five tons of rock, with an additional police presence to prevent looters. In the summer of 2019 the cave, a significant
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are deposited on the inside surface. Over time, this slow feed of mineral constituents from groundwater or hydrothermal solutions allows crystals to form inside the hollow chamber. Bedrock containing geodes eventually weathers and decomposes, leaving them present at the surface if they are composed
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When cut in half, visible bands corresponding to varied stages of precipitation may at times show patterns that reveal points of fluid entry into the cavity and/or varied colors corresponding to changes in chemistry.
221:, etc. There is no easy way of telling what the inside of a geode holds until it is cut open or broken apart. However, geodes from a particular area are usually similar in appearance.
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Geodes and geode slices are sometimes dyed with artificial colors. Samples of geodes with unusual colors or highly unlikely formations have usually been synthetically altered.
288:, where they are known locally as "potato stones". The term geode generally describes hollow formations. If the rock is completely solid inside, this would be classified as a
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Geodes can form in any cavity, but the term is usually reserved for more or less rounded formations in igneous and sedimentary rocks. They can form in gas bubbles in
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will impart rust hues to siliceous solutions, such as the commonly observed iron-stained quartz. Most geodes contain clear quartz crystals, while others have purple
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found in Brazil, Uruguay and
Namibia. Geodes are common in some formations in the United States (mainly in
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Geodes are found where the geology is suitable with many of the commercially available ones coming from
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316:'Crystal cave' is both an informal term for any large crystal-lined geode and also used for specific
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332:, discovered in 1999 in Spain. In 1999, a mineralogist group discovered a cave filled with giant
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of syn-genetic concretions and partial filling by the same or other minerals
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248:. Large, amethyst-lined geodes are a feature of the basalts of the
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Geode banding and coloration is the result of variable impurities.
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108:. Geodes are hollow, vaguely spherical rocks, in which masses of
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Video of a geode cracking using industrial soil pipe cutter
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40:-filled geode, shown from inside (top) and outside (bottom)
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matter (which may include crystals) are secluded. The
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Kentucky
Geological Survey (University of Kentucky)
421:"Geodes: The rocks with a crystal surprise inside!"
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546:Encyclopedia of Sediments and Sedimentary Rocks
348:resource and now named the 'Geoda de Pulpi',
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641:"Geodes – Small Treasure Vaults in Illinois"
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619:Indiana geode specimens, facts and stories
571:The Common Rocks and Minerals of Missouri
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201:crystals. Still others can have agate,
169:of resistant material such as quartz.
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597:Geodes: A Look at Iowa's State Rock
276:). Geodes are also abundant in the
639:Illinois State Geological Survey.
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573:. University of Missouri Press,
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152:, such as vesicles in basaltic
16:Hollow formation inside a rock
1:
569:Keller, Walter David (1961).
544:Middleton, Gerard V. (2003).
116:are formed by the filling of
629:Australian Museum Fact sheet
209:banding or crystals such as
124:by minerals deposited from
100:secondary formation within
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140:, or hydrothermal fluids.
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312:and regular quartz geodes
250:Paraná and Etendeka traps
156:; or, as in the American
600:. Iowa Geological Survey
96: 'earthlike') is a
26:Not to be confused with
584:restricted online copy
559:restricted online copy
320:locations such as the
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21:Geode (disambiguation)
483:"Definition of Geode"
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184:
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326:Cave of the Crystals
19:For other uses, see
530:Pough, Fredrick H.
338:Province of Almeria
322:Crystal Cave (Ohio)
126:hydrothermal fluids
532:Rocks and Minerals
328:(Mexico), and the
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594:Witzke, Brian J.
579:978-0-8262-0585-8
554:978-1-4020-0872-6
463:Dulcote, Somerset
122:subvolcanic rocks
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653:on 2007-09-27.
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459:"The Quarries"
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548:. Springer,
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510:. Retrieved
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428:. Retrieved
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278:Mendip Hills
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136:from water,
134:precipitated
128:; or by the
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512:1 September
425:geology.com
350:Pulpi Geode
330:Pulpi Geode
318:geoheritage
308:Very large
195:Iron oxides
138:groundwater
130:dissolution
102:sedimentary
77:; from
673:Mineralogy
662:Categories
492:2023-05-22
468:2017-12-30
430:2017-12-30
404:References
398:Thunderegg
388:Lithophysa
346:geotourism
294:thunderegg
264:, western
228:Occurrence
203:chalcedony
187:chalcedony
177:Coloration
166:carbonates
98:geological
678:Petrology
581:, S. 67 (
219:celestite
162:silicates
144:Formation
445:"Geodes"
356:See also
334:selenite
310:amethyst
282:Somerset
270:Kentucky
266:Illinois
262:Missouri
215:dolomite
199:amethyst
185:Reddish
118:vesicles
114:crystals
286:England
254:Indiana
242:Namibia
238:Uruguay
211:calcite
164:and/or
158:Midwest
110:mineral
605:Geodes
577:
552:
538:
487:Mindat
290:nodule
272:, and
246:Mexico
244:, and
234:Brazil
207:jasper
189:geodes
91:geṓdēs
85:γεώδης
38:Quartz
668:Rocks
651:(PDF)
644:(PDF)
342:Spain
205:, or
81:
46:geode
28:Geoid
575:ISBN
550:ISBN
536:ISBN
514:2022
274:Utah
258:Iowa
154:lava
104:and
292:or
280:in
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