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Thunderegg is not synonymous with either geode or agate. A geode is a simple term for a rock with a hollow in it, often with crystal formation/growth. A thunderegg on the other hand is a specific geological structure. A thunderegg may be referred to as a geode if it has a hollow in it, but not all geodes are thundereggs because there are many ...
A geode (/ ˈ dʒ iː. oʊ d /; from Ancient Greek γεώδης (geṓdēs) 'earthlike') is a geological secondary formation within sedimentary and volcanic rocks. Geodes are hollow, vaguely spherical rocks, in which masses of mineral matter (which may include crystals) are secluded.
The thunderegg, a nodule-like geological structure, similar to a geode, that is formed within a rhyolitic lava flow, were said by the Native Americans of Warm Springs to have been created by thunder spirits that lived in the craters of Mount Hood and Mount Jefferson.
Geodes are a vug-formed rock, although that term is usually reserved for more rounded crystal-lined cavities in sedimentary rocks and ancient lavas. [2] The word vug was introduced to the English language by Cornish miners, from the days when Cornwall was a major supplier of tin. [3] The Cornish word was vooga, which meant "cave". [3]
The world's largest known geode, a celestine geode 35 feet (11 m) in diameter at its widest point, is located near the village of Put-in-Bay, Ohio, on South Bass Island in Lake Erie. The geode has been converted into a viewing cave, Crystal Cave, with the crystals which once composed the floor of the geode removed. The geode has celestine ...
Vugs, cavities and geodes are all examples of open-space filling phenomena in hydrothermal systems. Alternatively, hydraulic fracturing may create a breccia which is filled with vein material. Such breccia vein systems may be quite extensive, and can form the shape of tabular dipping sheets, diatremes or laterally extensive mantos controlled by ...
Whole rock K–Ar ages from Geode Nunataks basaltic andesite lavas range between 59.9±1.41 and 41.3±1.01 myr. Whole-rock K–Ar ages from Finlandia Foothills basaltic andesites range between 50.2 ± 1.3 and 45.5 ± 1.3 myr. Contacts with other volcanic and nonvolcanic geologic units are not exposed. [3] [4]
Concretion rock with white core from the Middle Jurassic of Iran. Detailed studies have demonstrated that concretions form after sediments are buried but before the sediment is fully lithified during diagenesis.