A Heart Stone is an unusual type of ore mined from deposits which appeared in Solstheim in the Fourth Era. It's suspected that the deposits surfaced during the cataclysms of the Red Year; Master Neloth of House Telvanni suspected that the material came from Red Mountain and was flung along with other materials to Solstheim during its eruption. Even two centuries later, they still smolder with the heat of the mountain. These are the molten rocks that lay next to the Heart of Lorkhan for millennia, and some vestige of its power has seeped into them. Heart stones sometimes raise Ash Spawn from the bits of bone buried in the nearby ash. Through trial and error, one of his apprentices learned that a stone was needed to prevent an ash guardian summoned through Conjuration from attacking the caster. The stones can also be used for the enchanting purposes. Ildari Sarothril, a different apprentice of Neloth's, was killed during an experiment but was brought back to life when one of these stones was grafted to her. Ildari learned that a stone could be used to prevent necromantic spells from wearing off.
- For game-specific information, see the Dragonborn article.