10 • Marine Minerals: Exploring Our New Ocean Frontier 



At the current stage of preliminary re- 

 source assessment in the EEZ, little cre- 

 dence should be given to estimates of the 

 economic value or tonnages of seabed 

 minerals .... 



ronment and to inventory minerals occurrences 

 within U.S. jurisdiction, the potential value of de- 

 veloping and marketing technology for seabed min- 

 ing and shipboard processing systems should not 

 be ignored. It is possible — perhaps likely — that the 



major commercial seabed mining ventures may not 

 be in the U.S. Exclusive Economic Zone, but rather 

 in other countries' waters (small mining operations 

 have already taken place). In this instance, U.S. 

 innovation and engineering know-how applied to 

 developing seabed mining technology could place 

 the United States in a pivotal competitive position 

 to exploit a world market (probably modest in size) 

 for seabed mining equipment. Technological inno- 

 vation in seabed mining systems could also assist 

 the U.S. industry in maintaining a national capa- 

 bility to deploy such technology in U.S. waters or 

 elsewhere in the world when economic opportuni- 

 ties arise or if emergencies occur. 



MINERAL OCCURRENCES IN THE U.S. EEZ 



Only a miniscule portion of the U.S. EEZ has 

 been explored for minerals. However, several types 

 of mineral deposits are known to occur in various 

 regions of the U.S. EEZ (figure 1-3). These include: 



• Placers — accumulations of sand and/or gravel 

 containing gold, platinum, chromite, 

 titanium, and/or other associated minerals. 



• Polymetallic Sulfides — metal sulfides formed 

 on the seabed from minerals dissolved in su- 

 perheated water near subsea volcanic areas. 

 They commonly contain copper, lead, zinc, 

 and other minerals. 



• Ferromanganese Crusts — cobalt-rich manga- 

 nese crusts formed as pavements on the sea- 

 floor on the flanks of seamounts, ridges, and 

 plateaus in the Pacific region. They may also 

 contain lesser amounts of other metals such 

 as copper, nickel, etc. 



• Ferromanganese Nodules — similar in compo- 

 sition to ferromanganese crusts, but in the 

 form of small potato-like nodules scattered ran- 

 domly on the surface of the seafloor. Those 

 found within the EEZ in the Adantic Ocean 

 tend to be lower in cobalt content than deep 

 ocean manganese nodules in the Pacific 

 Ocean. 



• Phosphorite Beds — seaward extensions of on- 

 shore phosphate rock deposits that were laid 

 down in ancient marine environments. 



Since so litde is known about the volume in place 

 and the mineral content (assay) of most seabed de- 

 posits, most deposits are properly termed "occur- 

 rences" rather than resources. Not much more can 

 be said about a mineral occurrence other than that 

 a mineral has been identified, perhaps in as little 

 as one surficial grab sample. A few EEZ mineral 

 deposits have been investigated enough to be 

 termed "resources," deposits that occur in a form 

 and an amount that economic extraction is poten- 

 tially feasible. 



At the current stage of preliminary resource 

 assessment in the EEZ, little credence should be 

 given to estimates of the economic value or ton- 

 nages of seabed minerals that have been inferred 

 by some obsei-vers. Current information should be 

 interpreted cautiously to avoid implying a greater 

 degree of certainty than is justified by the sampling 

 density, sampling design, and analytical techniques 

 used. Misinterpretation of the results (i.e., by in- 

 ferring that the results of a small number of surfi- 

 cial samples are representative of an extensive, 

 three-dimensional deposit) of preliminary assess- 

 ments can lead to false expectations. 



Close-grid, three-dimensional sampling is needed 

 to adequately delineate and quantify mineral de- 

 posits in the seafloor. Sand and gravel, phosphorite 

 beds, and placers vary in depth below the seabed 



