Opal

Opal is a rare gem item used in crafting and as a valuable find from mining and treasure sources. It is most commonly obtained by mining Opal Ore Rocks with a Copper Pickaxe or better, but the rocks are very uncommon and remain rare even when the player’s Mining Licence level is high. The chance of finding them increases as the Mining Licence improves, making higher mining progression the best way to farm Opal from the overworld.

Other ways to obtain Opal include breaking open Thunder Eggs, which yields 4 Opals, and searching several special loot sources. It can be found with a low chance in the Quarry, inside chests in locked treasure rooms in the Deep Mine and Undergrove, and in buried chests on Island Reef. A Shiny Stone or Pretty Pebble can also be placed in the Stone Grinder for a small chance to produce one, and a Gacha Machine can yield Opal as well. Jimmy may sell Opal from his boat when his stock rotates.

Opal is also used at the Jewellery Table, so it is worth keeping a few on hand rather than selling every one you find. Because the item is tied to multiple rare sources, the most reliable method is still mining Opal Ore Rocks whenever they appear, with the other methods acting as bonus sources during exploration and looting.