Oil sands, or tar sands are an unconventional source of petroleum. The oil sands are a mixture of sand, clay and water in a dense and extremely sticky form of petroleum called bitumen . Natural bitumen is found in many countries, with the largest quantities in Canada , Kazakhstan and Russia . More @Wikipedia
Hover over any link to get a description of the article. Please note that search keywords are sometimes hidden within the full article and don't appear in the description or title.