Transcript
Here at Scurry Adventures we love geodes. They are full of surprises, and you don't truly know what they will look like inside until vou crack one open! The outside of geodes look like regular rocks and usually has a somewhat spherical shape. One question we get a lot is “How do geodes form?”
Before we answer this question, we want to let you know that we are not experts but are hobbyists. That being said we must first explain what a geode is before we explain formation. The word “geode” is derived from the Greek word “geoides” meaning “earth-like”. A geode is a rock which contains a cavity of empty space on the inside. If a mass of rock does not have an empty space, it is NOT a geode but a nodule. A nodule was once a geode but the minerals have completely filled in the space. The cavity in a geode is typically lined with crystals such as quartz, calcite, agate or other minerals. Not all geodes are round. In fact, some geodes have irregular shapes. Geodes can form in desert areas (common in the US) and areas where a volcanic eruption has occurred with a lava flow. The vast majority of geodes form in igneous rocks also known as volcanic rocks so we will focus on those today and talk about the sedimentary geodes in a later video. There are a lot of unknowns regarding geodes. It is undetermined how long it takes a geode to form (could be thousands to millions of years) and the exact timeline of formation of a geode is not completely known. Here are what some of the experts say regarding geode formation.
The first step in the formation of a lava flow geode is a volcanic eruption which occurs near or above the earth’s crust. As the lava flows out from a vent, it mixes with gasses such as carbon dioxide or sulfur dioxide. Most of these gasses escape the erupting material, but on occasion these gasses can get trapped inside the lava. This forms large bubbles within the lava. Volcanic gasses are not the only thing that can get trapped in lava. In certain circumstances, such as undersea eruptions or when lava hits a groundwater aquifer, large amounts of water can get trapped within the lava. Also other impurities can be trapped in the lava which can change the color of the crystals. As the lava cools, the gasses and water get trapped in a layer of recently cooled stone formed from the eruption. Whatever shape these bubbles were at this stage will determine the resulting shape of the geode. Due to the chemicals present within the rock, crystals begin to grow at this stage.
The longer the crystals take to cool, the larger they become. As these crystals grow, the gas and water is usually compressed until it finds a weak point in the rock and escapes. Sometimes the water gets trapped within the rock so when it is cracked open, the water is released. These are called enhydros. The hollow area remains, but it is now partially filled with beautiful crystals! It is the variety of mineral possibilities and impurities that make collecting geodes so interesting.
In the US, you can find geodes in California, Utah, Nevada, South Dakota, Florida, Missouri, Indiana, Colorado, Kentucky, Iowa and Arizona. Geodes can be found all over the world but predominantly in Uruguay, Brazil, Mexico, Argentina, Madagascar and Morocco.
If you check out our website ScurryAdventures.com we have geodes from Mexico for sale. We can crack your geodes before shipping or send them to you whole. If you live in the Oklahoma City area we invite you to come over and crack your own geode! You can find Scurry Adventures with their geodes and cracker at craft fairs and rock shows in Oklahoma. We hope you enjoyed this video and learned something new! Be sure to check out Scurry Adventures on Facebook and KZitem. Give us a like, comment and follow. Be sure to watch our older videos and follow us so you can see when we put out new content. If there is a topic you would like us to discuss on a future video let us know. Again, thanks for watching!
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