Crystal Nucleus

The  is a location in the Crystal Hollows, mainly used to deposit collected crystals from expeditions. Players can travel to main areas of the map using each of four corners, including the Magma Fields directly below the platform. After all five crystals are delivered to their respective statues, a treasure stash will appear opposite of the Topaz Crystal Statue. Treasure stashes are completely random, meaning each item listed isn't guaranteed to drop. Crystals are reclaimable as well to unlock more treasure stashes.

Crystals
To get the rewards the player needs to find and place five crystals. All the crystals are obtained in a different way. The progress can be tracked in the Heart Of The Mountain menu.

Jade
The Jade (green) crystal is obtained in by finding items with a metal detector (obtained by talking to any of the four NPCs there) in the Mines of Divan. Follow the Mithril Deposits caves to find this area.

Amber
The amber crystal is the second crystal. Find and talk to King Yolkar. You need three of the same goblin eggs, but they can be green, yellow or red. The eggs need to be stacked in other to give them to the king. There currently is a bug cousing some eggs not to be stacked. After obtaining an effect, you can enter the Queen's Den to obtain the crystal.

To get here, follow the Goblin Holdout caves.

Amethyst
To obtain the Amethyst (Purple) crystal you need to go in the Jungle Temple and enter the door which requires a Jungle Key, the door should be guarded by 2 guards, after opening the door you need to complete a series of parkour rooms, when you finish you should be able to get the crystal

Sapphire
The Sapphire (Blue) Crystal is obtained by giving 6 Automaton Parts to Professor Robot in the Lost Precursor City. After giving the parts the door next to him will open and you will be able to claim the crystal.

Topaz
The Topaz (Yellow) Crystal is obtained after defeating the magma boss Bal, located in the Khazad-dûm.

After defeating the boss the crystal will spawn near the boss.

It is recommended to bring some water bottles because drinking one will reduce the heat by 40, and some heat resistant armor (such as Heat Armor, Flamebreaker Armor, or the Bal Pet for direct heat resistance)