The black deposits produced in the system were mainly composed of iron sulphide and iron oxide.

系统产生的黑色沉淀物主要由硫化铁和氧化铁构成；

youdao

'We're quite lucky they weren't very good at washing up, these guys - and so they've left some carbonised remains of foodstuffs inside these pots, there are black deposits on the interior surfaces.

我们走运了，看样子这些绳纹人似乎不太擅长清洗厨具，所以在这些陶罐陶钵里头还残留有一些已经碳化了的食物残渣，就是这种器皿内部表面存留的黑色沉淀物。

youdao

An emigre returning after several years away says a gentle change is blowing across the country, like the wind that deposits black sand from the Karakum desert over Niyazov's white marble capital.

一个离开几年的流亡者回来说，温和的改变正在发生，就象是风把卡拉库姆沙漠的黑色的沙吹到niyazov的白色大理石首都。

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Miners can use underwater robots to dig up deposits left from "black smokers, " which are little towers of metallic sulfides that form after magma forces fluids with copper, gold and other metals through the seafloor.

WSJ: Exhausting the Earth's Resources? Not So Fast