All That Glitters

 is a Stranger mission in Red Dead Redemption II. The quest becomes available during Chapter 2.

Story
Máximo Cristóbal Valdespino. a self-proclaimed famous explorer can be found southwest of Horseshoe Overlook. He tells Arthur he traveled to the country to hunt for treasure but is looking to leave the United States tomorrow. He offers to sell Arthur a treasure map of the location where Jack Hall Gang's gold is stashed.

The map consists of three treasures that can be found in various locations: the first is located in Caliban's Seat, the second in Cotorra Springs, and the third in Lake O’Creagh’s Run.

Walkthrough
After meeting with Máximo, decline his first offer of $10 for the map for him to lower the price to $5. If you scared him away, robbed or killed him by accident, you can buy his map from any fence in the game.