EVAPORITES AND BRINES 



213 



evaporites remain to be discovered in the world. 

 These might increase world resources of their com- 

 ponents by 1 to 2 orders of magnitude above re- 

 sources in known deposits. 



BRINES 



Sea water, lakes, seas, and many shallow subsur- 

 face brines have known compositions. They are not, 

 therefore, "undiscovered," but they do represent 

 potential resources because processes capable of 

 extracting selected dissolved components at a profit 

 may someday be developed. Those bodies contain 

 large to virtually unlimited quantities of several 

 commodities. New extraction processes for many 

 substances are not likely to be developed out of 

 world necessity inasmuch as known reserves and 

 resources appear adequate for hundreds or thou- 

 sands of years. Some may be developed, however, 

 as new techniques allow some chemicals to be ex- 

 tracted more cheaply or closer to markets. 



Deep subsurface brines contain very large quan- 

 tities of dissolved substances, but few basins out- 

 side of known or potential petroleum and gas fields 

 have been explored. The geologic factors controlling 

 the distribution of valuable brines are not well under- 

 stood and the number of unexplored basins contain- 

 ing valuable brines cannot be reliably estimated. In 

 some areas, the amount of brine now extracted is 

 controlled by pet-.-oleum production. More could be 

 extracted if necessary, but the quantity cannot be 

 evaluated although it is known to be large. 



SUMMARY OF U.S. RESOURCES 



Evaporite resources of the United States, ex- 

 pressed as years supply at current rates of con- 

 sumption are shown in table 43. Although known 

 domestic resources of potassium compounds are 

 relatively low, Canadian resources are sufficient to 

 fulfill requirements of North America for thousands 

 of years. 



PROBLEMS FOR RESEARCH 



The abundance of evaporite and brine resources 

 means that no shortage is impending. Continuing 

 effort should be made toward finding new and more 

 economic deposits, however, because they would 

 supply large quantities of the basic chemicals re- 

 quired in industry and agriculture, and their cost 

 would be an important factor in the price con- 

 sumers pay for many products. For this reason it is 

 imperative to have not only resources, but resources 

 that would permit these chemicals to be produced 

 and transported to the consumer at low cost. The 

 main problems posed by resources derived from 

 evaporites and brines are that the costs of some are 



Table 43. — Evaporite and brine resources of the 

 United States 



[Expressed as years supply at current rates of domestic consumption] 



Commodity 



Undiscovered re- 

 Identified resources ' sources ( Hypotlie- 

 ( Reserves 2 and sub- ticaH and specula- 

 economic deposits) tive ^ resources) 



Potassium compounds 



Salt 



Gypsum and anhydrite 



Sodium carbonate 



Sodium sulfate 



Borates 



Nitrates 



100 years Virtually 



inexhaustible. 



_1,0004- years — Do. 



_500+ years Do. 



-6,000 years 5,000 years. 



.700 years 2,000 years. 



.300 years 1,000 years. 



'^ " " ' Unlimited (air). 



Strontium 

 Bromine _ 



Iodine 



Calcium chloride 

 Magnesium 



-300 years 



- Unlimited 



(air). 

 -500 years 



- Unlimited 



(sea water). 



-100 years 



-100+ years __ 

 -Unlimited 



(sea water). 



-2,000 years. 

 Unlimited 

 (sea water). 

 -500 years. 

 - 1,000 -f years. 

 Unlimited 

 (sea water). 



Specific, identified mineral deposits that may or 

 .s to extent and grade, and whose contained min- 

 erals may or may not be profitably recoverable with existing technology 

 and economic conditions. 



-Reserves: Identified deposits from whi( 

 profitably with existing technology and ui 



^ Hypothetical resources; Undiscovered i 

 recoverable or subeconomic grade, that a 

 existing in known districts. 



'* Speculative resources: Undiscovered mineral deposits, whether of re- 

 coverable or subeconomic grade, that may exist in unknown districts or 

 in unrecognized or unconventional form. 



undesirably high today and costs of others are likely 

 to increase in the future. These problems are results 

 of the uneven geographic distribution of deposits 

 throughout the United States and the world, and 

 the increasingly low-grade ores and the more com- 

 plex and expensive extraction processes needed to 

 utilize them. Discovery of new and more inexpen- 

 sively processed deposits is needed. The abundance 

 of known deposits of marine evaporites minimizes 

 the need to find new ones, and efforts should be 

 concentrated on locating the more valuable concen- 

 trations of minerals within the known deposits. In 

 contrast, a large percentage of the world's deposits 

 of nonmarine evaporites and brines are undiscov- 

 ered, and extensive programs of geologic study and 

 drilling will be needed to find them. 



Important to the geologic understanding of evapo- 

 rite and brine deposits are a knowledge of (1) the 

 variations in past positions of global climatic belts, 

 (2) the times of past fluctuations in global climatic 

 character, (3) the processes involved in the con- 

 centration and crystallization of evaporite com- 

 ponents from waters, and (4) the mechanics of 

 diagenesis that affect sohds and brines both imme- 

 diately and long after burial. Major obstacles to 

 the finding and development of new evaporite re- 

 sources stem from our imperfect understanding of 

 these phenomena, and research leading to an im- 

 proved understanding is essential. 



