shale basin and was deposited in shallow marine environments. The deposit is one of the world’s highest-grade deposits with more than 40% organic content and 66% conversion ratio into shale oil and gas. The oil shale is located in a single calcareous layer in thickness and is buried at depths from . The total area of the basin is about . Oil yield from Kukersite is 30 to 47%. Most of the organic matter is derived from the fossil green alga, Gloeocapsomorpha prisca, which has affinities to the modern cyanobacterium, Entophysalis major, an extant species that forms algal mats in inter-tidal to very shallow subtidal waters. Matrix minerals include low-magnesium calcite, dolomite, and siliciclastic minerals. It is not enriched in heavy metals. Reserves As source rocks for most conventional oil reservoirs, oil shale deposits are found in all world oil provinces, although most of them are too deep to be exploited economically. As with all oil and gas resources, analysts distinguish between oil shale resources and oil shale reserves. "Resources" refers to all oil shale deposits, while "reserves", represents those deposits from which producers can extract oil shale economically using existing technology. Since extraction technologies develop continuously, planners can only estimate the amount of recoverable kerogen. Although resources of oil shale occur in many countries, only 33 countries possess known deposits of possible economic value. Well-explored deposits, potentially classifiable as reserves, include the Green River deposits in the western United States, the Tertiary deposits in Queensland, Australia, deposits in Sweden and Estonia, the El-Lajjun deposit in Jordan, and deposits in France, Germany, Brazil, China, southern Mongolia and Russia. These deposits have given rise to expectations of yielding at least 40 liters of shale oil per tonne of oil shale, using the Fischer Assay. A 2008 estimate set the total world resources of oil shale at 689 gigatons — equivalent to yield of of shale oil, with the largest reserves in the United States, which is thought to have , though only a part of it is recoverable. According to the 2010 World Energy Outlook by the International Energy Agency, the world oil shale resources may be equivalent of more than of oil in place of which more than may be technically recoverable. For comparison, the world's proven conventional oil reserves were estimated at , as of 1 January 2007. The largest known commercial deposits in the world occur in the