Geode is referred to round and hollow rocks which are filled with crystal materials can be found in sediments of volcano cliffs. This rocks are created due to growth of crystal minerals inside the empty cavities of rocks. But if the growth of crystal continue in Geodes, it may fill the Geodes. Geodes have a shell made of lime and silicon and they are resistant against weathering.
There are several reasons why Geodes have holes inside them such as: the existence of bubbles while igneous rocks are cooling. Animals nest and rotting of trees roots in sedimentary rocks. When water penetrates inside this holes, water-soluble materials like silicon and Calcite, sediment in the rock and stick into its wall and make small crystals in the rock.
This process takes millions of years and beautifies inside of the rock. Silicate is one of the most abundant minerals in Earth’s crust and that’s why most of the Geodes are Quartz, but in Uruguay many Amethyst Geodes have been found that some of them are 3 meters tall.
Ruby Geode looks like a rock but when you look at it deeply, you can see beautiful crystals. Crystals of Ruby Geode are made of Quartz or Jacinth’s sediment but there are also Geode made of other mineral such as Calcite, Celestine and Dolomite. Most of the Geodes are created in empty small cavities inside the earth that are mostly made because of animals or roots of trees. The process of formation starts with a small lime stone or an Anhydrite and by passing the time waters and minerals penetrate the cavities and solidify mineral around the small stones. Due to solidification of sediments from waters and minerals (which happens several times) a crystal structure and the Geodes outer shell is created. Geodes are also created in the bubbles of volcanic rocks. Minerals are trapped in cavities that are sedimented by vapor and with each sediment a great amount of minerals become hard and make lime stone around the core of rock.
The creation of crystals is different based on amount and time of humidity’s sediment. In case water penetrates slowly and with less impurities, the core of Geode is greatly equalized with crystal, but if the sediment is made really fast, then cavities are formed with Quartz and agate.
The idiom “Geode” is taken from its Greek roots meaning “earths form” this name was given to them because of their natural and earthly forms. However some of them are oval. Geodes can be found all around the world especially in USA (California, Nevada, Illinois, Arizona, Missouri, Kentucky, Utah, and Iowa) but most of them are in deserts and volcanic areas.