Been recently exploring some of the old mines in the Harriman, NY area.

In looking at the yardage of rock that was removed, the question came up of how many yards or tons of rock had to be removed in order to realize a pound of iron? Obviously this would depend on geology, but what percentage would make it practical to continue mining vs abandon?

Thanks and be safe!

4r

For what it's worth (probably not much) in the tv series Deadwood, the character George Hearst (played by Gerald McRaney) says he won't bother with "the color" unless it's at least 4%.

I think he was referring to gold.