Oil shale is a type of mineral fuels in the form of shale With organic compounds called K Regensburg campsites in stonework. Usually dark brown to black.
The stone is a type of fuel oil and minerals in the form of an organic substance by schist, called kerogen mingle in the rock is typically dark brown to black.
fuel oil mineral stone is a type of rock that is in the form of Dan, by organic substances that are called Lower Mississippi begins south to be well-versed in meat is mixed with a dark brown stone is often to black