What marine resource has been rendered uneconomical due to the cost of excavation?
a. Magnesium compounds
b. Manganese nodules
c. Sand and gravel
d. Salt
ANS: B
There are different ways of mining manganese nodules. Unfortunately, none of the methods people
have come up with have made it cost effective to mine these nodules. There may come a point in time
when the mining of these nodules becomes economical. Information can be found in the section
Physical Resources.
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