Brazil has nine significant locations of oil shale deposits. The size, location and quality of oil shale deposits in the Paraíba Valley and the Irati Formation have attracted the most attention. These two contain an estimated 1.4 billion barrels of "in-situ" shale oil with total resources as much as more than three billion barrels. While the "Irati formation" deposit is the smaller of the two, containing an estimated 600 million barrels "in-situ" compared to 840 million in the Paraíba Valley formation, the former is more economically viable.