Oldschool Mammoth Axe q11 15^50

I was farming Minister Cho's HM and I got a gold 15^50 Q11 Mammoth Axe as a drop. I'd never even heard of it so I looked it up. It only drops oldschool from Shing Jae Island so I figured it must be worth something. Any idea of what it's worth would be a great help, thanks.

5-10k....................and it can drop from raisu palace chests.

Agreed, 5-8k.