""Like obsidian, but with a tad slimier."
Obsidium is an uncommon resource exclusive to Big Boom Peak, obtained with a drill.
Obsidium is a volcanic mineral similar to obsidian, but it is only found on specific areas in the Far, Far Range. Slime Scientists are not sure why Obsidium replaces obsidian in the Far, Far Range, but it is suspected that Obsidium is actually a combination of molten Jellystone and obsidian.
On the Ranch
Deposit Obsidium into the Lab's refinery where it can be used for crafting Slime Science gadgets.