Vintage Quincy Mine (Hancock) Check (1870) Located in Michigan, the Quincy Mining Co. has operated since 1846. The Quincy Mining Co operated primarily in Keweenas, as their company specialized in copper, and its demand skyrocketed through the Industrial Revolution, helping propel the company to success. As the competition increased, copper became more scarce, and so did the company's wealth, slowly declining until the 1960s when it slowed production and is now a historical sight. These checks date back to the company's early years in the mid to late 1800's and will never be made again.