The Jack Hall Gang treasure map is one of the first treasure maps you can find in Red Dead Redemption 2, and it leads to a decent payout, but you'll have some trekking to do to find it. You get the map from the "All that Glitters" Stranger mission.
As with all treasure maps in Red Dead Redemption 2, this one comes in multiple parts. You'll have to pair up the sketches on the treasure map with the locations and conduct a thorough search, but the rewards are usually worth it. It helps if you've got fast travel unlocked.
It appears that if you encounter Maximo and don't buy the treasure map, or kill him and don't loot it from his body, you should be able to buy it from a fence later in the game.
Jack Hall Gang Treasure Map - All that Glitters
On the cliff overlooking the Dakota River just west of Flatneck Station, you'll find a chap called Maximo, who's about to go off exploring. Get the treasure map off him for $10 (or rob him of it) and you'll be able to embark on the first part of this treasure hunt.
The first map depicts Caliban's Seat, which is just south of Valentine. You sometimes spawn here after restarting your game if you last played and quit around the town of Valentine, so you can use that as a shortcut.
Once you ride up you'll see a ridge to the east of it, where you'll have to leave your horse. At the top, looking towards Valentine you'll find a path that slopes down to the right.
Follow this, jumping across ledges and clambering until it looks like you can't go any further. It's here you'll be able to search and find the second part of this map, along with a pearl necklace.
The second map depicts what looks like a circle and some steaming rocks. It's actually Cotorra Springs, which you'll find in the north of the map, north of Fort Wallace. If you take the train from Valentine you can get off at New Handover, Bacchus Station. Then it's just a short ride along the tracks.
Once you get to Cotorra Springs, position yourself at the bottom pile of rocks, so you have a geyser to your north, northeast and northwest. At the pile of rocks, you'll find the third Jack Hall Treasure map.
There's also a Legendary Animal to hunt here if you feel like facing off against a wolf. You may as well while you're here.
You now have the third Jack Hall Gang Treasure Map. You'll now need to head to the east Grizzlies and specifically O'Creagh's Run.
There's an island in the middle lake here and you're searching on the south of it, underneath a rock. It's here you'll finally find 2 Gold Bars that are worth a lot of money. Take them to a fence and you can sell them for $500 a piece.
While you're here, you should go fishing to stock up on food, because the lake is absolutely teeming with fish.
You can also check out our guide to the best weapons in Red Dead Redemption 2. If you want to get rich quick, find a fence or want to know where to hunt legendary animals, then check out our complete Red Dead Redemption 2 guide here.