Crystalarium

The Crystalarium is a crafted item that slowly duplicates a single inserted gem or mineral. It can replicate any Gem except a Prismatic Shard, as well as Foraged Mineral and Geode Mineral items. The machine’s behavior is explained in the Lost Book Technology Report!. Once an item is placed inside, the Crystalarium produces infinite copies of that item over time, and the inserted item can be recovered later by breaking the Crystalarium with a tool.

A Crystalarium is awarded for donating 50 Minerals to the Museum. It can also be found in treasure rooms in the Skull Cavern. Because the machine never consumes the original item, it is especially useful for turning a rare mineral into a permanent source of income, gifts, or trade items.

Crafting and production times are affected by the game’s unusual clock: time passes differently between 2:00 am and 6:00 am, so listed replication times are approximate. The output rate also depends heavily on the item inserted. Some of the most notable options include:

• Diamond, which has one of the highest sell values and takes the longest to reproduce.
• Jade, which is valuable on its own and useful for trading.
• Ruby, Emerald, and Aquamarine, which are strong choices for steady profit.
• Quartz, Earth Crystal, and Frozen Tear, which reproduce quickly but sell for less.
• High-value minerals such as Helvite, Neptunite, and Bixite, which make the Crystalarium especially profitable if you already have spare copies.
• Marble, Basalt, Obsidian, and other geode minerals, which can also be duplicated.

For maximizing use, Crystalariums are commonly devoted to minerals that can be exchanged with the Desert Trader or given as loved or liked gifts. In practice, this makes the machine useful even when the item’s direct sell price is not the highest, because it can generate a reliable supply for trading or relationship building. Since the Crystalarium works indefinitely, placing multiple machines with different minerals is an efficient long-term strategy for both profit and utility.

Because the inserted item can be removed at any time, a Crystalarium can be reconfigured whenever you need a different mineral. This makes it flexible enough to support early-game income, museum collection support, gifting, and late-game trading setups without permanently sacrificing the original item.