458 



OTHER SURFACE DEPOSITS 



The unconsolidated surface sediments of the ocean floor include 

 several known deposits which could become potentially economical. 

 The pelagic sediments of deep, offshore waters are classified as red 

 clays if their organic content is less than 30 percent, and as oozes 

 if their organic content is more than 30 percent. Their widest distri- 

 bution is in the Pacific Ocean, usually at depths averaging between 

 6,000 and 17,000 feet. 



Although now uneconomical, these clays and oozes contain some 

 potentially useful constituents such as calcium carbonate, alumina, 

 iron oxide, and silica. They literally cover the ocean floor, and are 

 estimated to be in the order of thousands of billions of tons. 



Nearer to shore, and in shallower water, unconsolidated green sands 

 (glauconite) are found abundantly in areas of slow detrital deposi- 

 tion. Glauconite sand is a hydrous potassium iron-silicate with a 

 small amount of potash content. It has been sampled off the coasts of 

 Africa, the Americas, Australia, Japan, New Zealand, the Philip- 

 pines, Portugal, and Britain. Green sand mined from land has been 

 used as a water softener and soil conditioner. 



Barite, a barium sulphate mineral, is another surface deposit 

 which occurs in nodular form like phosphorite and manganese. 

 Barite concretions have been dredged from the continental margin off 

 the coasts of Ceylon, southern California, and the Kai Islands in Indo- 

 nesia. The concretions range up to two pounds in weight and assay 

 around 75 per cent barium sulphate. 



Large deposits of barite are known on land, which makes the ocean 

 barite unimportant at this time. However, barite is being mined off- 

 shore Barite Island in Alaskan waters 20 to 80 feet deep, with known 

 reserves in 120 feet of water. Current production from this operation 

 alone is 1,000 tons per day m ; daily production of primary barite in the 

 United States averaged about 2,600 tons for 1970. 30 



Deposits Below the /Seabed Surface 



The subsurface deposits of the seabed are those contained within the 

 structures of consolidated sedimentary and basement rocks. They can 

 be viewed in two groups, related primarily to the methods of their 

 extraction. On the one hand, petroleum, natural gas, and sulphur are 

 extracted through holes drilled into the sea floor. On the other hand, 

 coal, iron ore, and vein deposits are extracted in conventional mining 

 manner by driving shafts and drifts into the seabed from adjacent 

 land areas. 



Undersea mines operated from land entries, either from shore or 

 from artificial islands, have been in use for centuries. Magnetite veins 

 are mined near Jussaro Island, Finland, and an extensive undersea 

 iron ore is mined from Bell Island in Newfoundland. Land-entry coal 

 mines are also operated in England, Japan, and Nova Scotia. How- 

 ever, these operations are closely tied to land and do not figure promi- 

 nently in the I'nt lire of the seabed. 



20 Joseph F. Stevens, "Mining tbe Alaskan sons," Ocean Industry (November 1970), 

 pageo 47 -49. 

 30 U.S. Bureau of Mines. Commodity Data Summaries (January 1971), pages 10-11. 



