Extraction of oil shales and tar sands

A process for the extraction of oil shales and tar sands comprising heating the shale or sand in the presence of an extractant gas selected from the group consisting of

• ethylene,
• carbon dioxide,
• aromatic hydrocarbons having a single benzene ring,
• aromatic hydrocarbon having a single benzene ring substituted with not more than 4 carbon atoms in a substituent group,
• alicyclic hydrocarbon having at least 5 carbon atoms and not more than 12 carbon atoms,
• aromatic hydrocarbon having 2 aromatic rings,
• aliphatic hydrocarbon having at least 5 carbon atoms and not more than 16 carbon atoms,
• phenol derived from an aromatic hydrocarbon having up to 8 carbon atoms,
• alcohol,
• aldehyde,
• ketone,
• ether,
• ester,
• aliphatic mono, di- and tri-amines having at least 4 and not more than 10 carbon atoms,
• acyclic aliphatic amines and
• aromatic amines having a benzene ring in the absence of externally supplied hydrogen to extract extractable constituents therefrom, separating the extractant and extract from the residue and recovering the extract from the extractant characterized in that the extractant is a gas phase extractant and the extraction is carried out at a temperature within the range of 0.degree. to 550.degree. C at a pressure not less than the critical pressure, the extractant being above its critical temperature by not more than 200.degree. C and said temperature being within the range of 350.degree. to 550.degree. C when extracting oil shales.