This. That said, it seems there's a bug with gold gravel in the version in Unleashed since the smeltery doesn't want to smelt it. Is anyone else having that problem or am I just unlucky. To add to that, I'm doing the drying rack recipe of turning zombie flesh into leather but it doesn't seem to work either even though mDiyo said that it was supposed to take around 5 minutes.Yes, the Smeltery will process other coppers and tins through the magic of Ore Dictionary.
Edit: Nevermind on the drying rack one, seems that was disabled in 1.4.1.6
Edit 2: Also, for the gravels I'd suggest leaving aluminum in cause it can be a bit hard to find underground. Its uses are rather limited, but even so I prefer to note use gold where I can until I have a good amount.