In the summertime intense light and heat cause the algae Dunaliella salina to produce carotenoids as a protection against free radicals, due in turn to high metabolism.

This turns the salt pans brilliant shades of violet, scarlet, magenta, and emerald (see photo in reference).

[2] The most plausible explanation of the financial prominence of the province of Shanxi during the Ming and Qing dynasties states that its salt works at Xiechi Lake fostered mercantile activity that would ultimately need banks, these banks would become the piaohao.

In 1370 the army of the Ming began using its salt rights, known as yan yin, which were initially redeemable only at the Xiechi Lake, to pay for transporting provisions to Chinese soldiers stationed on the Great Wall.

This policy that benefited the Shanxi merchants remained in effect long enough for them to accumulate a substantial amount of wealth for themselves, ultimately leading to their dominant position in the Chinese financial market during the Qing dynasty.