From the other board:

"Ore" vs "Tailings"

There's been a bit of discussion as to what to call the piles- tailings, ore, tailspin (a new one to me), etc. Tailings are what remains after ore has been "processed". Nowadays, that usually means ore in which gold and silver have been removed so that only milligrams/ton, at most, are left behind. SFMI's ore has been processed in a sense- some of it was run through a stamp mill, and all of it (at least the above ground stuff) has been "processed" in the sense that the miners in the late 1800s-early 1900s picked through it and only selected the best stuff (probably meaning significant amounts of visible gold) as worth hauling by mule to be further processed- either at one of the mills set up on the mountain or further down. It's unclear whether the stuff still in the tunnels has even gone through that relatively crude selection process. It's been reported that only ore with more than about 2oz Au/ton made it through the "selection" process used- so the remaining material should be very high grade- up to 2oz/ton or more. Even the material put through the stamp mill should have a lot of gold and silver left. In the only reference to the efficiency of stamp mills I've been able to find so far, only about 40% of the gold (and silver too?) was removed by mechanical "concentration", with most of the the gold being removed by mercury amalgamation (50%) or cyanidation (5%) (Metallurgical and Chemical Engineering, Dec 1914, Company reports, pp 744-745, link). Even with these methods, about 6% of the gold was left behind. I assume the stamp mill leftovers SFMI is starting to mill were not subject to amalgamation, so they may have still have over half of the gold left in them!

So yes, technically it's OK to call the above ground stuff "tailings"- although most companies would like to have ore with the grades that we should soon be seeing. Me, I prefer to call it ore.