Finding a Firestone in Monster Hunter Wilds is an important step in upgrading your weapons, especially if you're favouring the fire-based Quematrice tree. Since this is one of the first weapon types accessible that deals elemental damage, chances are you probably crafted one to set monsters ablaze.
This rarity three weapon upgrade unlocks after you defeat the Rompopolo in the Oilwell Basin as part of the main story. So, if you want an even better fire weapon to go with your scorching surroundings, you're going to need that Firestone.
Monster Hunter Wilds Firestone location
You can get Firestone from mining outcrops in the Oilwell Basin area. However, this might take you a few tries since they're a rare material in Low Rank—you'll know when you get one because your hunter will perform a special little animation where they look at the stone they've just pulled out of it.
If you're looking for a place with plenty of mining outcrops in the Oilwell Basin, you can harvest two in area 4 and another two in area 6, both of which you'll find directly up the road from Everforge base camp. Once in area 4, climb up the scalable wall to enter area 6 with the other two. Harvesting these nodes will also get you to Dragonite Ore the Quematrice upgrade requires, though you'll have to slice off and harvest its tail for the final ingredient.
You should also explore the bottom of the map where the lava pits are for more outcrops, though don't forget to have a Cool Drink to stop your health from decreasing here. On the bottom layer of the map there are four mining outcrops in area 13, two in area 16, and a final two in area 17. Harvest all of these and unless you are extremely unlucky, you'll find a Firestone.
If you are really unlucky and don't get a Firestone, you can either wait for the mining outcrops to respawn (their timer is shown if you hover over them on the map), change time by resting in your tent, or progress the story quest, since defeating the final boss of chapter two will give you a Firestone as a quest reward as well.
Once you arrive in High Rank, Firestone won't be anywhere near as rare and will drop more often from mining outcrops in the Oilwell Basin. You'll also sometimes be able to get them from the Material Retrieval feature if you unlock that with Aida.
