Ghana and India, both large suppliers of the Western World in the past, are now exporting only limited quantities of low or medium grade ore. The ore mined in Mexico is mostly for internal usage, but part is exported in the form of sintered nodules. The CIS, which as the USSR was the largest supplier of manganese ore at the beginning of the century, is now left with low grade ore reserves which have to be upgraded for commercial use. Only a limited amount of these reserves is exported, in amounts which are likely to decrease and perhaps even disappear in the future. There are also large manganese reserves on deep ocean floors in the form of polymetallic nodules.
Quantitative estimates vary considerably, depending on the assessment method used.
Recovery will be difficult and very expensive. These nodules are now seen as potentially valuable resources for the long-term future.