FREE: Septarian Nodule Buffalo

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Septarians were formed approximately 100 million years ago when the Gulf of Mexico reached what is now Southern Utah. De-composing sea (shell) life, killed by volcanic eruptions, had a chemical or molecular attraction for the sediment around them, forming mud balls. Tide and wave action rolled the balls around increasing the size of many of them. As the ocean receded the balls were left to dry and crack. Because of their bentonite content they also shrank at the same time, trapping the cracks inside. They were then covered by sediment. The ocean returned de-composing more shell life above them. As this de-composed calcite from the shells was carried down into the cracks in the mud balls, calcite crystals formed. A thin wall of calcite was transformed into aragonite dividing the bentonite heavy clay (shale) exteriors from the calcite centers. Because of this dividing wall (septum in Latin) the geodes are called Septarians. Septarians are composed of Calcite (The Yellow Centers), Aragonite (The Brown Lines), and the outer grey rock is Limestone.
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