Some crude oil, natural asphalt, and petroliferous rock are appreciably radioactive, but little is known about the actual uranium content and the chemical nature of the uranium compound or compounds in these materials. Semiquantitative spectrographic analyses of the ash of 29 samples of crude oil, 22 samples of natural asphalt, and 27 samples of oil extracted from petroliferous rock indicate that metals such as vanadium, nickel, copper, cobalt, molybdenum, lead, chromium, manganese, and arsenic are consistently present--at some places in exceptionally high concentrations--in this type of organic matter. The chemical analyses show that the uranium content of crude oil is consistently much lower than the uranium content of the natural asphalt and oil extracted from petrolif rous rock. The uranium content of the ash of these 78 samples ranges from about 0.001 per cent to about 10 per cent; the uranium content of the total oil or asphalt ranges from less than 0.001 to 32,410 parts per million (3.24 per cent).

The association of uranium with organic materials may have a direct bearing on the genesis of some types of uranium deposits. Additional research on (1) the distribution of uranium and associated metals in crude oil and asphalt, (2) the chemical nature of the uranium-bearing compound or compounds in crude oil and asphalt, (3) the carbon-hydrogen ratios, nitrogen and sulphur contents, and chemical properties of these uraniferous materials, and (4) the conditions under which the metals can be leached from natural asphalt and petroliferous rock might aid in the search for new uranium deposits.