Septarian nodules are concretions which form when a binding agent, usually a carbonate mineral, forms a cement-like mass which binds together other minerals, rocks or stones in the vicinity. If the cement does not wholly block all the cavities thus formed, water can percolate, often depositing other minerals, particulalry quartz. This gives the nodules complex internal structures, with many different zones and areas of crystalisation.

Description: This is a classic septarian nodule, in which the binding agent is Barite. This accounts for the heavy weightof the specimen. Unlike many nodules, this one has not been cut and polished, but cleaved by  sharp blow. This exposes the complex imternal structure far better than polishing. One of the outstanding features is the heavy quartz crystalisation. This has the most beautiful yellow colour, coupled with regular small sugar-like crystals. Also notable are several larger rock masses which have become trapped by the cementation process.

Location: Gory Swietokrzyskie, Poland.