This form of Hematite has alternating layers of Hematite and Chert (which is a form of sedimentary rock). Hematite is the raw Iron Ore that is mined in the Upper Peninsula, however this particular form was discarded because it was difficult and expensive to seperate the chert from the Hematite. These slabs have been coated with a polyurethane epoxy to give it a "wet" polished look.