Coffee tin found in old mine

Hi.....I had earlier (several weeks now) posted a coke bottle we had found in the eastern Sierra Nevadas' at about 9000', it was loose in a rock slide...since then I thought I'd post some items we found in a long abandoned mine, which included a work room with hearth and black smithing, a kitchen and bunk area as well as the shaft.....this mine was hewn out of native granite at about 10,000 feet and was not visible because it was on a ledge with a vertical drop of about 1000 feet to the talus below. All the rooms and shaft were within the native rock. This tin was in the kitchen area along with a Folgers baking powder tin and utensils. Newspapers used to insulate the bunks and stashed for toilet use had varying dates, the oldest being a Sacramento Union dated March 28, 1874. I'd like to nail the year, or a close spread, as we would like to ascertain the last year(s) the mine was worked. As the entire situation was dug,chipped, blasted , and shoveled out of the solid rock(they were following a seam of quartz) and stayed long enough to construct and supply a sizable work-shop complete with a HUGE bellows and 99lb anvil(in my possession, took us three years at one trip a year to hike that anvil and bellows out of there) this mine must've been productive. well thanks for any dates you may come up with thanks