In an ultrabasic rocks in North Jiangsu, corundum was first discovered and some was up to gem grade.

苏北某地超基性岩中，首次发现了红刚玉，少量已达宝石级。

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In an ultrabasic rocks in North Jiangsu, corundum was first discovered and some was up to gem grade.

苏北某地超基性岩中，首次发现了红刚玉，少量已达宝石级。

youdao