Septarian nodules form when calcite is deposited in the center of a solidifed mass of sediment, similar to a geode. Our septarian plates are slices of these nodules, displaying the light carbonate center amid the darker surrounding sediment. These beautiful pieces are excellent for display in the home or classroom, and make a great addition to any collection. These plates are approximately 8x6" dimensionally, and weigh just under 2 pounds. Samples vary naturally, and may not look identical to those pictured. If you reach out to us before you buy, we will send a picture to ensure you are receiving a specimen you'll like.