In Rarity Miner, Lost Keys are needed to unlock Lock Chests that will eventually reward you with various useful resources and items. However, finding a Lost Key can be a daunting task due to its limited availability and fixed spawn location, which is why I’ve put together this guide to help you find it in Rarity Miner.

Lost Keys are usually found in caves at depths between 440m and 1,000m, particularly in the Basalt to Tuff biomes. You will usually find three or four keys in a cave, and they are relatively easy to find in Rarity Miner. For example, I found one of the Lost Keys 700 meters below the surface.

It’s worth noting, however, that their spawn locations aren’t fixed, meaning you’ll come across them randomly as you explore. Once you collect a Lost Key, it’ll be added to your inventory, and the Cave Index will also update, so you don’t have to remember the exact depth.

As mentioned, Lost Keys can unlock Lost Chests in Rarity Miners which contain useful rewards. Unfortunately, finding these chests is a challenging task as they only spawn in Gleam Cave. So far, I haven’t gotten anything valuable from them, but I was lucky enough to get a Celestial from one of the chests. So, it’s safe to assume that the rewards are random, and the rarity you receive is purely a matter of luck.