The volume of miners and industries using copper in the 20th century presented an exponential growth. Mining tends to extract the highest grade resources first, once they are the most profitable. With the intense activity achieved during the last century, the higher grade non renewable sources were quickly depleted, forcing the industry to start exploring lower grades sources to satisfy the demand.
It is also noteworthy that mining copper of higher quality causes more damage to the environment, having its protocols and restrictions consequently addressed by the legislation. Therefore the costs of mining 5% copper might be outweighed by a higher margin of profit from 0.5% copper which also is less damaging to the environment.
I think the answer's Twitter
It gave empires new technologies and attracted more people
<span>Credible, because a historian student could have some idea on different topics, and then discover new information that eventually led the student to rethink their ideas. In particular, the sentence is credible because it is possible to admire several pieces in the British Museum related to Julio Ceasar.
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Biased. The sentence, while could be absolutely written by a historical scholar, should not be included in an article, unless the article is an essay where the scholar expresses an opinion, and even then it should be justified and not simply stated as it appears here.
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Biased. The sentence seems more probable to be said during a personal conversation of some sort, considering the personal tone of the statement, and the fact that is made considering only the speaker's viewpoint without any evidence to support the claim.
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Credible. While the sentence sure is not the best from an academic viewpoint, in a blog it is not usual to use a form of expression that is less codified than what is used in scholars papers. Moreover, it is credible that a historical blogger could want to engage its readers in that way, thus making the statement credible.</span>
I'm sorry, what text? Could you post the passage please?