Nitrogen is found throughout the soils and atmosphere in many different, organic and inorganic, forms. The Nitrogen Cycle is the process by which atmospheric nitrogen enters the soil, is transformed by microbes, and re-enters the atmosphere (volatilization) and plants (assimilation).
How Does Nitrogen Enter the Soil?
Before nitrogen can be used by plants, it must enter the soil. Atmospheric nitrogen is forced to the ground by rainfall. Also, urine, solid and liquid waste from living organisms and living organisms that have died are deomposed by bacteria and fungi. The nitrogen from these sources then enter the soil. Commercial fertilizers are another source of nitrogen.
What Happens to Nitrogen in the Soil?
Plants cannot use organic nitrogen. Bacteria and fungi are needed to transform this unusable organic nitrogen into a usable form. Although most nitrogen fixation is completed by bacteria, some is accomplished through lightning strikes. Since ammonia is fatal to most plants, bacteria convert this ammonia (NH4) into nitrates (NO3) and nitrites (NO2). At this time, the nitrogen can be assimilated into the plant, leached into the ground water or be transformed into a gas and re-enter the air.
In very wet soils, the oxygen content is low. The bacteria in these soils take the oxygen out of the nitrates (NO3) and produce nitrogen gas. This process is call denitrification. Through a process called volatilization, the gas re-enters the atmosphere.
Geodes are a great way to view and learn about the formation of rocks. They occur in sedimentary as well as some volcanic rocks too. These geological rock formations are most commonly limestone on the outside, while the inside is hollow and full of quartz crystals. If there is no air pocket in the formation it is called a nodule instead of a geode.
How Do Geodes Form?
A geode starts off as a bubble or a void left by an animal burrow, tree root, or something else. Water is trapped inside of the void, which contains silica precipitation that has other minerals or elements present in it such as calcite, iron or manganese. The basic crystals of a geode are made of quartz (silicon dioxide) and are colored based on the contents of the surrounding soil. Over thousands of years different layers of silica precipitation cool and create different layers of crystals. There is no way to tell what is on the inside of a geode without cracking it open. You can view the process of cracking open a geode below.
How to open a Geode
This video demonstration shows cracking open a Geode with a pipe cutter.
If you want to learn how to break open your own geode, check out this page at the Geode Gallery.
Where you can find Geodes
Geodes are found in areas where there had been:
Volcanic activity at one point.
Weathering had taken place that allowed the accumulation of minerals and organic substance.
Over at The Geode Guys, they have a list of some locations that are known to have geodes.
Where you can Purchase Geodes
Heath Scientific can provide you with a solid geode or crack it open for you.