What metal was discovered in Ancient China and how did it improve their way of life?

Explanation is in the file

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the earthquake in haiti was a magnitude of 7.0 according to the u.s geological survey yet the smaller earthquake in haiti killed more than 200,000 and left more than 1.2 million people homeless. the chile earthquake was a magnitude of 8.8 and 500 times more stronger but chile's earthquake only injured 712 people.