substitutes. Hydrochloric acid could be used for steel pickling. Nitric acid, at a cost, could be used by 

 the fertilizer industry where the introduction of sulphur is not required. Hydrofluoric acid may be used 

 instead of sulphuric acid in manufacturing higli-octane gasoline. 



Potential from marine sources.'*^ Table 2 summarizes the various known and future potential sources 

 of sulphur in the continental shelves. 



Elemental sulphur obtained from sulphur-bearing salt domes by the Frasch process in the Gulf of 

 Mexico has been and will continue to be the most prohfic offshore source in the United States. Although 

 other sources of sulphur are available to supplement supply from salt dome deposits all are more 

 expensive to mine or recover than Frasch sulphur, with the one exception of sulphur recovered from 

 sour gas."*"* Elemental sulphur is recovered from domestic sour gas at the rate of 1.2 million tons a year, 

 a level that will rise but not sufficiently fast to meet rising demand because this source is completely tied 

 to natural gas demand rather than sulphur demand. To shift from salt dome sulphur to pyrite, to 

 recovery of sulphur or sulphuric acid from base-metal ores, or recovery of sulphur-bearing compounds 

 from liquid or solid fuels, can only result in a significant rise in the price of sulphur. 



The amount of salt dome sulphur to be found in the continental shelves and slopes of the Gulf of 

 Mexico is highly problematical. It is not yet known how many salt domes lie in the region nor how many 

 contain sulphur-bearing caprock. Little is known about the geology critical to the discovery of sulphur 

 deposits, because in the past all deposits were discovered by drilling in the search for oil. This was 

 demonstrated during the last three years when sulphur companies failed to find deposits in offshore 

 blocks they had nominated and for which they paid $33 million to the Government for exploration 

 privileges. 



Exploration for offshore salt dome sulphur deposits is controlled by U.S. regulations geared largely to 

 the proprietary interest of the Government and designed to apply to the oil and gas industry. Yet the 

 chance for discovery of sulphur is much lower, and therefore the cost of exploration much higher than 

 in the petroleum industry. Out of a total of 329 salt domes known onshore and offshore in 1966 only 

 21 (1 in 16) were found to contain sulphur in economic amounts. This compares with a 1 in 10 

 discovery ratio for petroleum. Both the rate at which salt dome sulphur deposits will be found on the 

 continental shelves and the cost of their discovery (reflected in cost of sulphur) are determined by 

 Government policy and procedures. 



THORIUM 



Uses. The most important present use of thorium metal is in magnesium alloys. Thorium nitrate is of 

 great importance in the fabrication of incandescent gas mantles. Nickel alloyed with thorium oxide 

 possesses superior strength and corrosion resistance to temperatures of 2400°F. The oxide is also used as 

 a catalyst in the petroleum and chemical industries. Thorium probably will become an important nuclear 

 fuel as it can be converted in a nuclear reactor to U-233 which is fissionable and can sustain a chain 

 reaction. 



Present levels of utilization of thorium oxide (ThO^) in short tons. 



World (1966 production) 800 



United States (1966 non-energy demand) 85 



World demand cannot be estimated, because several countries class thorium as a nuclear-energy 

 element and information on its disposition is classified. An undetermined portion of the production goes 

 into'goverrunental stockpiles. U.S. production is withheld to avoid disclosing company confidential data 

 on monazite production. 



''^V. E. McKelvey et ah, "Potential Mineral Resources of the United States Outer Continental Shelves," unpublished 

 report of the Geological Survey to the Public Land Law Review Commission, March 1968. 



A. J. Bodenlos, Geological Survey, written communication, 1968. 



VII-155 



