Complex sentence: This practice, which is believed to have taken place in 1859 and 1860, was halted after the eruption of a public scandal; some Mint employees were striking and selling restrikes of classic American coins for their own profit.
Split into simpler sentences: This practice, which is believed to have taken place in 1859 and 1860, was halted after the eruption of a public scandal. Some Mint employees were striking and selling restrikes of classic American coins for their own profit.