Quartz over Chalcedony Natural Crystal Geode-Morocco »
Posted By geodecrystal6 5 months, 1 week ago in Business & FinanceWith its light lavender color and sparkling crystal caverns, this amazing Quartz Chalcedony Geode is incredible!Dimensions are for closed Geode.
Geodes can form in any cavity, but the term is usually reserved for more or less rounded formations in igneous and sedimentary rocks, while the more general term "vug" is applied to cavities in fissures and veins. They can form in gas bubbles in igneous rocks, such as vesicles in basaltic lavas, or as in the American Midwest, rounded cavities in sedimentary formations. After rock surrounding the cavity hardens, dissolved silicates and/or carbonates 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 of resistant material such as quartz.
Most contain clear quartz crystals, and others have purple amethyst crystals. Still others can have agate, chalcedony, or jasper banding or crystals such as calcite, dolomite, celestite, 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 any one locality usually have a more restricted variety of interior mineralization.
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.
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