Septaria refers to a specific form of concretion, which is a hard, condensed mass of matter created by the precipitation of mineral cement within the spaces between particles, commonly found in sedimentary rock or soil - concretions have been considered geological curiosities since at least the 18th century, and their wide diversity of appearances and forms have led their discoverers to interpret them as dinosaur eggs, alien leavings, or man-made artifacts.
Septaria are angular cavities or cracks found on concretions, and they can arrange themselves in many different beautiful patterns. The exact cause of septaria remains unknown, although speculation suggests that earthquakes may be involved. The most impressive example of septaria that we know of would be the Moeraki Boulders in New Zealand, which feature septaria up to 3 meters in diameter.
This particular septaria sample has been tumbled on one side to clearly show the form and color of the septaria as it manifests in the mass from which it was taken. A great addition to any rock or mineral collection, and a good teaching tool for demonstrating different unique geological formations.
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