If you have crushed the rock and looked at it under magnification and can't see any visible gold then the gold may not be in metallic form. Maybe the gold exist as a compound within the rock. It could exist in what looks like the iron part of this story. From the looks of that test solution the solution looks irony chloride color. Then you added stannous which reduced it to that brown color there (Iron) in your test. That would be my guess..... don't know. If you had that much iron in your solution then chances are it (Gold) never went into solution in the first place and is still on the residue (Rocks) from the leach. That's before you even start to discuss the grinding or fineness of the rock or proper roasting. A lot lot of things could have gone wrong.