You will have to get the sacred hide from the Jukari ritual cave.
The cave is far west of the Jukari village, it is on the map.
You should follow the south cliff wall until you cross the lava.
Ask Prof. Rafkin if you are having trouble crossing the lava.
(You did bring the fire extinguisher from the lab, didn't you?)
You can get some emeralds from the cave, they may come in handy.