Hi there,
It's awful hard to tell from pictures sometimes, and that's the issue with trying to tell exactly what you've got from your pictures.
As for highly obvious signs that what you have is gold, it doesn't look like it, but as H-2 Charlie has suggested, one way to find out (it would ruin your chunk of rock of course) is to finely crush the one you think is gold, then pan it out.
By doing that, you'll be able to check out how any gold-coloured particles in the pan move: if they are sluggish, and don't hardly want to move after you've panned the material down to the super-heavies, you've got a better chance of ID'ing gold by its specific gravity. For example, if your gold-coloured particles easily move in the pan, and if they exit the pan's crease quickly before the other heavies, they're not likely gold.
If you've never panned before, watch some good Youtube videos.
All the best,
Lanny