Fake gold is plaguing even the banks and financial houses.
Tungsten has the same density as gold and is easy to buy, so the bad guys make a tungsten brick and then coat is with real gold. You can’t tell the difference after that, unless you drill into the bar or try to cut it in half.
You might need that level of sophistication to fool SnakeDoc's marks over at Target, but I'd guess that the density of the "gold bar" in this case was closer to lead than tungsten, and possibly had just a little whiff of battery acid and propane too.