Recently with the help of the National Park Service I was able to identify and locate some additional information about this mine.
This is an old hard rock mine just off the Carbon River Road past the Mt. Rainier Park entrance. The mine was owned by the Washington Mining and Milling Co. ca 1899 and was a copper mine.
Several structures existed near the mine as late as 1951, which included six buildings and incline railway. None of the building structures exist today.
Previously this mine had been sealed by boards over the entire entrance with no access or view inside the mine. Recently the NPS replaced the entrance with a grate so you can walk into the tunnel several feet and see into the tunnel and track remnants clearly.
This mine tunnel is very large and tall in comparision to a mine like Clipper.
It would be a great mine to explore, it is however sealed with an iron grate.