A Qián Lóng T#333;ng B#462;o (#20094;#38534;#36890;#23542;) coin. From Wikipeida:
During the first few years of the reign of the Qianlong Emperor China had suffered from a shortage of cash coins due to the contemporary scarcity of copper, but soon Yunnan's copper mines started producing a large surplus of copper allowing the Qing government to swiftly increase the money supply and minting more coins at a faster pace. In the middle of the Qianlong era as much as 3,700,000 strings of cash were produced annually. In 1741 coins were ordered to be made of an alloy of 50% copper, 41.5% zinc, 6.5% lead, and 2% tin to reduce the likelihood of people melting down coins to make utensils, all while the Qing government encouraged to sell their utensils to the state mints to be melted into coinage. The addition of the 2% tin caused the Chinese people to dub these cash coins qingqian (#38738;#37666;, "green cash").
By the end of the Qianlong era, Yunnan's copper mines started depleting the production of cash coins, and the copper content was debased once more. 1794 all provincial mints were forced to close their doors, but subsequently reopened in 1796.
During the Battle of Ng#7885;c H#7891;i-#272;#7889;ng #272;a in 1788 special Qián Lóng T#333;ng B#462;o coins were minted with An nan (#23433;#21335;) on their reverse sides as a payment for soldiers.