Polished Septarian Freeform Mineral SpecimenBuy Septarian Crystal Mineral Specimen This polished Septarian freeform mineral specimen would be a great addition to your home or office. It has a beautiful pattern from every angle. Order it today for yourself or give it as a gift to a cherished loved one. Septarian, a sedimentary rock, is also known as "Lightning Stone. " It is composed of compacted hard matter, such as minerals cemented in between the spaces of other particles, and is found in