Extent and Distribution of the Resources 
Three major classes of mineral resources are 
found on the continental margin: dissolved minerals 
in seawater, minerals in unconsolidated deposits that 
occur in a variety of locations from coastal beaches 
to the deep seabed, and minerals in consolidated 
deposits in bedrock. 
Commodities in seawater are basically freshwater 
and minerals dissolved as salts, or in elemental form. 
Freshwater is also commonly found as submarine 
springs and constitutes a potential future source. The 
value of freshwater obtained from seawater in 1970 
was estimated at $9.2 million.1*® 
Unconsolidated deposits are defined as naturally 
occurring concentrations of minerals that are not 
hardened and are amenable to recovery by dredging. 
On the continental shelf (to water depths of 200 
meters), unconsolidated deposits of major interest 
are nonmetallics, including sand and gravel, glass 
sands, lime shells and calcareous algae phosphorite, 
and aragonite; heavy minerals including alluvial tin, 
iron sands, and titanium sands; and native elements 
including gold, platinum and diamonds. On the con- 
tinental slope (to depths of 2,000 meters) unconsol- 
idated deposits of major interest include phosphorite, 
carbonaceous muds, and metalliferous muds. 
Extraction of construction materials from offshore 
sources in 1973 constituted a $102.1 million indus- 
try, estimated to grow to $181 million in 1985; sand 
and gravel mining amounted to $65.6 million in 
1973, and shell recovery and processing for use as 
an aggregate added another $36.5 million.1® 
Consolidated bedrock deposits of interest occur as 
surficial deposits of coral, barite, and phosphorite 
crusts and deeply buried deposits of coal, iron ore, 
sulfur, potash, and various metallic salts.29° 
Table 4-12 provides a classification of dissolved, 
unconsolidated, and consolidated resources that are 
known to be in the ocean. Detailed knowledge of 
marine deposits is very small. Only a small percent- 
age of the continental margins and deep ocean basins 
has been surveyed for hard minerals. Before the full 
potential of these minerals can be realized, the tech- 
nological and engineering capabilities to locate and 
assess them must be improved and applied. Based 
upon present geological understanding of the nature 
of the continental margins and deep seabeds, how- 
ever, substantial deposits may be discovered. 
Potential for Mining on the Continental Shelf 
The potential for discovery and exploitation of 
marine hard minerals on the continental margin is 
high and the variety of deposit types is of the same 
order as that on land. Some marine mining opera- 
tions on the continental margin are already eco- 
nomically viable, as indicated above, others are likely 
to be so within the next decade, both in deeper 
water and farther from land. 
Minerals on the United States continental shelves 
that possess the potential for early economic devel- 
opment are the surficial deposits of sand, gravel, and 
calcium carbonate, placer deposits of titanium and 
gold, and marine phosphorite deposits. Based on 
geological and geophysical surveys performed by 
government and academic organizations in the past 
few years and the limited amount of industry infor- 
mation available, the National Academy of Sciences’ 
Marine Board Panel on Operational Safety in Marine 
Mining concluded in 1975 that the following sites 
may have commercial mining potential within two 
decades :7°" 
1. Gulf of Maine—potential for lode deposits, 
188 U.S. Senate Committee on Commerce. The Economic 
Value of Ocean Resources to the United States. Robert R. 
Nathan Associates, Inc., Washington, D.C., Government Printing 
Office, 1974 p. 30. 
chiefly sulfides in shallow waters, and some 
potential for sand and heavy minerals. 
2. Massachusetts Coast—parts of Cape Cod Bay 
and Buzzards Bay have good potential for sand, 
rare earth heavy minerals, and possibly coal. 
3. New Jersey-New York Bight—known sand de- 
posits. 
4. Southeast Atlantic Coast—known beach re- 
source of heavy mineral sands, but the sand 
potential of the seaward Outer Continental 
Shelf lands is incompletely known. 
5. Gulf of Mexico—potential for hard minerals on 
the Outer Continental Shelf appears to be 
limited as a whole, although the U.S. Geolog- 
icial Survey has identified abundant black sands 
(including titanium-bearing minerals) off the 
Texas coast. Oyster shells may prove to be a 
resource on the Outer Continental Shelf in the 
189 Ibid. p. 42. 
190 M. J. Cruickshank. ‘‘Mineral Resources Potential of Con- 
tinental Margins,” in The Geology of Continental Margins, edited 
by C. A. Burke and C. L. Drake. New York: Springer Verlag, 
1974, pp. 965-1000. 
191 National Research Council, Panel on Operational Safety 
in Marine Mining, Marine Board, Assembly of Engineering. 
Mining in the Outer Continental Shelf and in the Deep Ocean. 
Washington, D.C., 1975, pp. 19-20. 
IV-81 
