Remember Me
forgot your password?

What is a Geode?

The formation of Geodes takes place over millions of years and involves several different geological processes.

Hollow Rocks

So, let's start at the beginning: how do you get a hollow rock with lots of sparkling crystals inside? Geodes start their lives as a hollow bubble inside a layer of rock. The bubble could be from air inside explosive volcanic rock or it could come from the hollow remains of animal burrows or tree roots.

What About The Crystals?

Geodes that form from air bubbles inside of volcanic rock are pretty easy to picture. Think about the small air bubbles you see in pumice. Now, imagine just one of those bubbles completely surrounded by black or red volcanic rock. As rain pelts down on the hot bubble, the chemicals in the rock are slowly released into the water. Some of the water soaks through the hard, rocky outside of the bubble and is trapped for a moment on the inside. As the mineral-rich water moves on through the bubble, tiny crystals are left behind, clinging to the sides of the bubble. Millions of years pass while this in and out flow of water gradually builds crystals inside the empty space. The crystal formations might become large single crystals or tightly packed micro-crystals, so small that you can't even distinguish one from another.

An Animal's Home

Let's check out the development of our animal burrow bubble... Long after the animal has moved on or the tree has died and its roots have rotted away, the sediments that surrounded the hollow are being covered up by layers and layers of sediment hundreds of feet think. Eventually the weight of these layers has caused the sediments to turn into rock: sedimentary rock. Just like our volcanic bubble, this animal burrow bubble is host to mineral-filled water flowing in and out through the hollow space. And just like the volcanic bubble, a wide variety of crystals are taking shape inside the animal's former home.

Time Marches On

Fast forward to modern times. The water-soaked land where our bubbles began has become a vast desert where wind howls and the sun beats down. The ground, covered by rocks and scrubby brush yields up unusually shaped rocks. Today, you've found a good field of them and have three nearly-round specimens to crack open when you get home.

All Geodes Are Not Created Equal

The first one is quite hollow but for a nice layer of medium-sized blue crystals. These dugway geodes have bands of blue and pink. The colors come from the different minerals that flowed through the bubble so many millions of years ago. Another specimen is nearly solid all the way through. The microcrystals have formed wide bands of different colors and the tiny opening at the center has a thin ring of pointed crystals. Yet another is completely filled with solid rings of browns, reds and pinks. So, you've really found two geodes and one nodule. Nodule is the name for these round forms when they are filled solid.

Quartz, Calcite, Or What?

Most geodes have interiors made of either quartz or calcite. Quartz crystals are silicates. Silicates are the most common mineral in the crust of the earth. Over 90% of the minerals present in earth's crust are silicates. With this said, you can imagine that silicates are a pretty big group with lots of variation in terms of specific chemical composition.

Calcite's main ingredient is calcium carbonate CaCO2: dissolved calcium and carbon with some of the oxygen from the water thrown in.

Small variations Can Make A Big Difference

Now, add in a trace of iron or magnesium or copper and, voila, you have color variation.
Magnesium traces in calcite forms a nice pink dolomite layer, while magnesium in silicate accounts for the purples of amethyst.

Heat Can Change It

Now if your geode was close to a lot of heat, that could change the color, too. An amethyst that gets a lot of heat loses its purple color and becomes a soft yellow or citrine. You can see why there are so many color possibilities.

A Day In The Life

So, that little geode you're holding has had quite a journey getting to your hand. Treasure it for its beauty, but also for its history and the complex composition of minerals that made it. You're holding millions of years of work in your hand...enjoy touching the miracle of our earth's creation.

Claudia Mann
Find more information on Geodes at www.rocksandminerals4u.com. See Geodes for Sale
Rate this Article: 3.1 / 5 stars - 7 vote(s)
Print Email Re-Publish

Add new Comment



Captcha

  • Latest Education Articles
  • More from Claudia Mann

Returning College Student Scholarships - Free Money For The Jobless

By: Jazmine Young | 26/11/2009
What you can do in a troubled time like this is to take advantage of all the free scholarship programs available. It's free money for people that are willing to do something for themselves and to better their families.

Returning College Student Scholarships - Get Money Even If You Are Jobless Today

By: Jazmine Young | 26/11/2009
Most employers look unfavorably on job applications with a lengthy amount of time on unemployment.So you can easily figure out that the next time when you're applying for a job your application is going to more than likely at the bottom. If you are unsure of what to do in this situation, the next best thing that I can suggest to you is to go back to school.

Returning College Student Scholarships - Get $10,000 If You Happen To Be Jobless

By: Jazmine Young | 26/11/2009
You are more than likely in the same situation with millions of people out there. You have been working hard for your boss for decades on end and now you happen to find yourself out of a job.

Returning College Student Scholarships - Get Back To School Before Your Unemployment Runs Out

By: Jazmine Young | 26/11/2009
Most employers look unfavorably on job applications with a lengthy amount of time on unemployment.So you can easily figure out that the next time when you're applying for a job your application is going to more than likely at the bottom. If you are unsure of what to do in this situation

Returning College Student Scholarships - Stop Waiting On Your Unemployment Checks And Just Get Free Money For School

By: Jazmine Young | 26/11/2009
Or you just might be in a situation when there was only one income coming in and now that income has disappeared. And now you and your family are wondering what to do next.

Returning College Student Scholarships - Get $10,000 Even If You Are Unemployed

By: Jazmine Young | 26/11/2009
If you are unsure of what to do in this situation, the next best thing that I can suggest to you is to go back to school.

Returning College Student Scholarships - Win $10,000 Before The Deadline

By: Jazmine Young | 26/11/2009
Most employers look unfavorably on job applications with a lengthy amount of time on unemployment.

Returning College Student Scholarships - Get Back To School For Free

By: Jazmine Young | 26/11/2009
Or in some cases you might come from a household where there is only one source of income coming in and all of a sudden that income is gone. And now you and your family are wondering what to do next.

Teaching History - Alternatives to Traditional Methods

By: Claudia Mann | 27/12/2008 | Education
I learned history in a traditional school program. We studied California history in the fourth grade and US history in the fifth grade and, in general, history was organized and presented by geography in expanding circles. When I was taking courses in the history of Western Civilizations in college I found...

Amazonite - Extraordinary Feldspar

By: Claudia Mann | 06/10/2008 | Education
Amazonite has a soft green to blue green color, often with thin white streaks interlacing the green. It forms blocky prismatic or tabular crystals with angles that are not quite ninety degrees. Because of its natural beauty it is used to make jewelry and other ornamental objects. Amazonite has a...

The Triassic Period a Time of Transition

By: Claudia Mann | 20/06/2008 | Education
The Triassic Period begins the Mesozoic Era. The mass extinction event at the end of the Permian period ended 90% of the species on earth at that time. The plants and animals that survived would repopulate the planet. The Age of Reptiles The Mesozoic Era is called the Age of Reptiles. But...

The Mesozoic Era

By: Claudia Mann | 02/06/2008 | Education
The Mesozoic Era begins at the end of the Permian Period. Mass extinction had eliminated most of the species of life that had existed throughout the Paleozoic Era. The Continents At end of the Paleozoic Era the land that would become the continents of Europe and Asia crashed into North America. By...

Sedimentary Rocks

By: Claudia Mann | 26/05/2008 | Education
Sedimentary rocks are classified as clastic, chemical, and organic sedimentary rocks. The rocks in each group form by completely different processes. Clastic Sedimentary Rocks Clastic sedimentary rocks are formed from sediment. Sediments are tiny broken bits and pieces of rock that settle out of air or water. Weathering All rocks are subject to weathering. Weathering...

The Paleozoic Era

By: Claudia Mann | 14/05/2008 | Education
The Paleozoic Era is seen in the fossil record as an explosion of life forms. The Cambrian Period marks the beginning of an era with thousands of new life forms in the ancient seas. Prior to the Cambrian period fossils are extremely rare but after about 540 million years ago...

Igneous Rocks

By: Claudia Mann | 13/05/2008 | Education
Igneous...ignite! And that's just what happens when igneous rocks form. Fiercely hot molten rock from deep inside the earth pushes its way out and lights everything in its path on fire. As the firey liquid cools, it forms igneous rocks. Rock types are organized, or classified, according to how the rock...

Submit Your Articles Free: Signup
Article Categories




Use of this web site constitutes acceptance of the Terms Of Use and Privacy Policy | User published content is licensed under a Creative Commons License.
Copyright © 2005-2008 Free Articles by ArticlesBase.com, All rights reserved. (0.35, 6, w2)