An arrastra is a simple and primitive gold milling device. Heavy stones are dragged over gold ore to crush it. Mercury and water are added to the floor of the arrastra to create an amalgam and capture the gold.
There is some mystery about who built and used this arrastra. A small inclined shaft is up on the hillside above the arrastra, and a couple of prospects are in the area. The arrastra could have been built to mill ore from these prospects. Perhaps the ore played out too quickly, and the miners moved on before using the arrastra heavily.
