- “Whenever any rock or mineral was needed for characters or locations, I reviewed them with my wife, who is a geologist. She aided greatly in producing better references. We found great inspirations in places such as the Naica and Gypsum caves in Mexico and from the Batu Caves in Malaysia.”
- ―Alfonso Blaas, Art Director[src]
Heartstones are gigantic magic luminous gems, they have healing powers and have several properties like being used to restart the Earth or give more power to Trolls like Gunmar.
After Gunmar and his army were banished to theDarklands, some trolls traveled to America aboard the Mayflower and eventually found a new Heartstone underneath what would be known as Arcadia Oaks. From this, they built the Trollmarket around the new Heartstone.
Trollhunters (Part One)
Barbara Lake was wounded and taken to the Heartstone, prior to the loss of all memories made between the joining of herself and Stricklander’s fates and the present. This includes all memories of trolls.
Trollhunters (Part Two)
When Gunmar took over Trollmarket, he was also granted access to the Heartstone. This enabled him to drain its energy to regain his former strength, causing the gigantic crystal to turn black like the first Heartstone that spawned the Skullcrusher.
Trollhunters (Part Three)
When Gunmar managed to retrieve the Staff of Avalon, it is revealed that Morgana was imprisoned in a secret chamber underneath the Heartstone. Gunmar tried to free her but Merlin had a safeguard in his staff that would only allow human hands to use it in reciting the trollish incantation. Usurna later captured Stricklander and Barbara, the latter threatened by Gunmar to force the former to use the staff. Stricklander managed to purposely let the Staff's energies run wild, allowing him and Barbara to flee. This forced Gunmar to steer the energies towards Morgana's prison, freeing the Eldritch Queen.
In unleashing the Eternal Night, Morgana's spell destroyed the Heartstone, rendering Trollmarket uninhabitable. After the Eternal Night war, Jim and the other trolls venture to New Jersey in search of a new Heartstone.
3Below (Part Two)
Rise of the Titans
The Heartstone is a source of life and sustenance. It has the power to sustain life force to all trollkind, preventing them from crumbling to stone. It can also heal the sick and the injured. The Arcane Order and their titans have the ability to summon the Heartstone in order to restart the universe.
- According to Welcome to the Darklands, there are Heartstones within the Darklands. Gunmar’s throne is actually carved from one. This would make sense because it’s the Trolls' original homeworld. However, since the dark realm is decaying from both Gunmar's corruption and the Earth's mantle, all the realm's Heartstones are dying, making their power insufficient.
- As revealed in Rise of the Titans by Blinky, Arcadia Oaks houses the last surviving primordial Heartstone since First Creation, thus marking Arcadia as "the center of the universe" and explaining why the town's constantly inhabited/attacked by trolls, aliens, wizards, and other various supernatural creatures.