Fordite: an anthropocenic mineral "formed from the built up of layers of enamel paint slag on tracks and skids on which cars were hand spray-painted (a now automated process), which have been baked numerous times.
Natural Blue Obsidian (raw) Obsidian is a very special stone. It is not a true mineral. It is actually a volcanic glass that forms when molten lava cools too rapidly to crystallize. It consists mostly of Silicon Dioxide.