Septarian

A Septarian is a mass of a mineral substance, a sedimentary geode that formed on sea beds millions of years ago.  When they dried out they cracked.  These cracks filled with another mineral, especially calcite.  Morrocan Septarians are usually black and brown, while the ones from Utah are filled with golden calcite.  Same concretion process, different mineralizations.  We have mostly Morrocan - although we do often find exceptional specimens from Utah.