Looks like a $1.00 gold Liberty round coin. Minted by a private mint, not the US mint. A California gold piece from the gold rush. Should be in the Red Book.
A fractional gold coin is any gold coin that weighs under 1 troy ounce, so the answer to your question would be yes. !4 K means that you're coin is 58% gold. I'm not sure if its a fake of some coin, or just a coin I've never seen. It definitely not U.S. coinage, because the only coin they had then that was $1 gold was the Indian Princess Head. Hope that helps.
California fractional gold coin, and a nice one! Here's some info. 1868 ROUND LIBERTY BG-806 G25C MS | Coin Explorer | NGC
