Geode
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- There is also a line of microprocessors called Geode.
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Geodes (Greek geoides, "earthlike") are geological formations common to the United States (Indiana, the Keokuk area of Iowa and Kentucky), Brazil, and Mexico. Essentially rock bubbles with internal crystal formations, the exterior of a geode is generally limestone or a related rock, while the interior contains quartz crystals and/or chalcedony deposits. Other geodes are completely filled with crystal, being solid all the way though. These types of geodes are called nodules.
Geologists do not yet have a widely accepted theory about how geodes are formed, but it is believed geodes can form in any cavity that is buried. These can be bubbles in igneous rocks, pockets under tree roots, or even animal burrows. Over time, the external wall of the cavity hardens, and dissolved silicates and/or calcites are deposited on the inside surface. Over time, this slow feed of minerals allows crystals to form inside the hollow chamber. Then, over millions of years, the geode makes its way back to the surface through normal geologic processes.
The size of the crystals, their form and shade of color can vary greatly, making each geode unique. Some are clear quartz crystals, and others have rich purple amethyst crystals. Still others can have agate, chalcedony, or jasper crystals. There is no way of telling what the inside of a geode holds until it is cut open or broken apart.
A large geode roughly the size of a minivan was discovered in Put-in-Bay, Ohio in the early 20th century. It is known as Crystal Cave, and tours are possible during the summer.de:Druse (Mineralogie) pl:Geoda zh:晶洞