Septarian's are very useful for healing work. They give us the "Big Picture" prospective when trying to process different events or situations in our lives. Yellow Calcite is a Solar Plexus stone that supports our sense of self. The brown and black Aragonite add a grounding and stabilizing energy. I will intuitively choose a beautiful piece for you. Each stone measures between 2.5 to 3 inches and weight between 4.5 to 5.5 ounces. Although often called septarian nodules, this sedimentary rock is more technically a concretion. A concretion is a spherical, egg shaped, or irregular mass that forms around a nucleus. They often develop radial cracks that get filled in by other minerals. Their geological formation is still a matter of debate. Madagascan septaria are gray to brown limestone with yellow calcite and brown to black aragonite. Some pieces have colorless baryte.