Gold in desert

Not sure for digging, but there is more then enough on the surface. and you only need it for the piano and one or two more things, so you don't really need much. just go around and watch for rocks with yellow lines...

The best gold source is deep cavern around -500. Here you will find many exposed gold vein to easy collect them. Deep caves is a alternative too to find exposed gold vein.

It’s spawns at almost all levels, but as Bamse said, the deep water caverns between-480 and -500 will yield the most gold. You can simply walk around and find it on the walls.