Please find below the locations of the three chunks of adamantite in Darksiders III, these are needed to upgrade a weapon to +10 and are easily obtainable toward the end of your first playthrough once you have gathered all of the hollows.
Serpent Hole - Haven, North End
Face the church from the Serpent Hole and turn left (where the teleporting demon is at the end) Run to the giant root and grapple to the root on the opposite side.
Use the Fire Hollow and grapple-swing across two more roots to reach the balcony ahead. There’s a Luminous Visage here.
Turn around and swing again from this balcony to a different branch, then turn the corner and enter the building on the other side. Use the Force Hollow to break through the barrier. You’ll find the Chunk down the stairs inside next to a dead angel.
Serpent Hole - Bonelands, Cargo Ship
Go back past the crater where the kraken was to the acid pool area nearby and cross it using the Storm Hollow. Then go left and around to the back of the next building, you may have to fight the griffin again on this path. Go to the back-corner of the building ahead and wall-jump up the shaft with the Stasis Hollow.
Up here, swap to the Force Hollow and roll across the magnetic surface. At the end, jump across the floating containers in the acid lake and reach the small island with the chunk.
Chunk #3: Scar, Chasm Overlook
Jump down past the stasis walls to the end of the conveyor where the machinery and a few demons are. Use the Stasis Hollow to freeze the grinders, and move down between them. The chunk is in the open space beneath them, there is also a human around the corner at the end.
Hope this helps!