Bitumen is a black or dark-colored (solid, semi-solid, viscous), amorphous, cementitious material that can be found in different forms, such us rock asphalt, natural bitumen, tar and bitumen derived from oil, which is referred to as petroleum bitumen. In order to understand how bitumen is formed in nature, we need to go back to more than 360 million years ago. Fossil fuels formed during the Carboniferous period, when giant swamp forests dominated many parts of the Earth. Many microscopic organisms lived, died, and decayed in these forests and formed the basis for the production of coal deposits. With the accumulation of sediment layers and their gradual transformation under heat and pressure over many years, great bituminous coalfields created.
These ancient deposits are now the source of natural bitumen in various countries, including Canada, Venezuela, and Oman. Known also as oil sands, the deposits are now a mixture of sand, clay, and water, saturated with a dense and extremely viscous bitumen.