Present levels of utilization of all forms of calcium carbonate in millions of short tons. 



World ( 1 966 production) 4,000 (estimated) 



United States (1966 demand) 595 



(21 million tons of oyster shell 

 was produced in 1965 in United States) 



Ranges of demand projections to the year 2000. 



Potential from marine sources. ^ ^ Land resources of calcium carbonate rocks are so abundant and 

 widespread that no serious attempt has even been made to determine reserves.^ ^ However, the land 

 sources are by no means everJy distributed, and some large urban areas have no nearby land source. 

 Owing to the high cost of transporting calcium carbonate materials from distant land sources, expanding 

 urban areas located in coastal areas have looked to the sea for an alternate source of supply. Potential 

 materials are oyster shells, calcareous rocks such as coral, calcareous sands and calcareous ooze. 



During 1966 about 20 miUion tons of oyster shell were produced from the sea floor adjacent to the 

 United States. Most of this came from Texas and other Gulf Coast states but large amounts were 

 recovered from San Francisco Bay and lesser amounts from areas off Maryland, Virginia, and 

 Pennsylvania. All the shell deposits mined along the U.S. coast have been located in sheltered bays and 

 lagoons. They are generally covered by overburden and may be as much as 25 feet thick.^'' The size and 

 location of reserves are considered local trade secrets. Deposits of oyster shell are probably also present 

 offshore but they may be smaller than those in bays and lagoons. A minimum of 100 million tons of 

 shell may Ue on the Continental Shelf off the Gulf coast. 



Calcareous reefs and sands are common along the coasts of southern Florida, Puerto Rico, the Virgin 

 Islands, and the Hawaiian Islands. Only the Hawaiian Islands of these four areas has a shortage of readily 

 available calcium carbonate deposits on land. However, the cheapness of sea transportation relative to 

 land transportation could make importation of, for example, Florida calcium carbonates attractive in 

 some cases to fairly distant consumers. 



Little information is available on calcareous sand reserves off the Hawaiian Islands. However, the high 

 cost of calcareous sand from land based sources in Hawaii (nearly $4 per cubic yard) favors the 

 initiation of offshore recovery from lagoonal sands and muds and from coral reefs. 



Calcareous ooze is fairly common in the Florida-Puerto Rico area and is beUeved to have a fair 

 potential because it is relatively easy to recover. 



P. G. Cotter, "Lime and Calcium," in Mineral Facts and Problems, Bureau of Mines Bull. No. 630, 1965. 

 ^■•Mero. 



VII-148 



