Specular Hematite is the raw iron ore that is mined in the Upper Peninsula. The high grade ore like these specimens were 65-70% pure and was shipped as is on the ore boats. When underground mines became too expensive to run, they switched to open pit mining and most of that ore was low grade (around 30%) and needed to be processed into pellets. Each slab is coated with a polyurethane based epoxy to give it a glass-like surface. It's hard to tell from the pictures but in the light, specular has a gorgeous sparkle to it!