This is an absolutely stunning item. Weighing just over 1.2kg. Please see pictures for size in inches. Septarian or septarian nodules are concretions containing angular cavities or cracks, called "septaria" which have become filled with calcite and aragonite.
A concretion is hard, compact mass of rock that often forms around decaying organic matter. In the case of septarian nodules the concretions formed around decaying sea-life in a marine environment. The exact mechanism for how the cracks form in the concretions is a mystery.
One possible mechanism is the dehydration of the clay-rich core of a concretion causing it to shrink and crack. Another is the cracks being due to the expansion of gases produced by the decay of organic matter within a concretion. Earthquakes have also been a suggested as yet another mechanism. The cracks in the concretions are then filled in with minerals such as calcite (yellow) and aragonite (brown) and sometime pyrite causing the very interesting patterns, which have often been described as dragon's skin. They are frequently found as geodes with hollow, calcite crystal filled cavities. More rarely the fossils that originally started the formation of the concretion are still preserved in the septarian. The item "SEPTARIAN GEODE EGG. STUNNING PIECE 1.2kg" is in sale since Sunday, February 11, 2018. This item is in the category "Collectables\Rocks, Fossils & Minerals\Crystals". The seller is "clickkassabian" and is located in Southend-on-Sea.This item can be shipped to United Kingdom, Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Australia, United States, Canada, Japan, New Zealand, Hong Kong, Norway, Indonesia, Malaysia, Mexico, Singapore, South Korea, Switzerland, Saudi arabia, South africa, United arab emirates, Chile, Antigua and barbuda, Bangladesh, Belize, Bermuda, Bolivia, Barbados, Brunei darussalam, Cayman islands, Dominica, Ecuador, Egypt, Guernsey, Gibraltar, Guadeloupe, Grenada, French guiana, Iceland, Jersey, Jordan, Cambodia, Saint kitts and nevis, Saint lucia, Liechtenstein, Sri lanka, Macao, Monaco, Maldives, Montserrat, Martinique, Nicaragua, Oman, Pakistan, Peru, Paraguay, Reunion, Turks and caicos islands, Aruba.