Ether powder

Below the wheel, there was a spin option with 1000 credits cost. Thankfully, there was no cooldown timer.

The eight metals are Adamantium (200 gold coins), Mithril (100 gold coins), Celestial Bronze (500 gold coins), Neosteel (60 gold coins), Orichalcum (20 gold coins), Trinium (28 gold coins), Plutonium (15 gold coins), and Radium (180 gold coins).

Compared to the mining of these rare metals, 1000 credits cost was too cheap but the problem arrives after it lands on something.

For example, once the arrow landed on Adamantium, the mining will start with extracting 1gm of metal per hour continuously, which means Mark would be able to earn more than 8.7kg of Adamantine if he doesn't touch the mining system for a whole year.