manganese concretion

• 锰结核,锰质结核

manganese concretion的用法和样例：

例句

1. But despite millions of dollars of investment, the commercial extraction of manganese nodules never became reality.
   但是尽管拥有数百万美元的投资，锰结核的商业化开采始终未能实现。
2. Unlike manganese nodules, which are like golf balls scattered across the sea bed, these deep-ocean deposits occur in small areas around extinct hydrothermal vents.
   与锰结核像高尔夫球洞一样分散在海底不同的是，这些深海矿物层则在熄灭了的海底烟囱附近小范围内存在。