Ardurine

Ardurine is the name given to a new type of quartz. To those in the know, it is known as a soul gem. It has a crystal shape, the ideal shape being a six-sided prism terminating with a six-sided pyramid.

Formation

Ardurine is formed in very unique circumstances. The cave system where this crystal can be found is located within The Frozen North, where temperatures can reach up to -40 °C (-40 °F) in the winter. The cave protects it from these temperatures, though. Furthermore, the caves are naturally warm, because of steam and heat from a vulcano deep under ground. Under normal circumstances, the caves are around 25 °C (77 °F).
However, Ardurine is special, because of its synergistic relationship with a chemosynthetic alien species, called Arduroceus. This species has an incredible low metabolism, giving it a very long life-span. Because it covers almost the entirety of Ardurine spikes and crystal formations, it forms an insolative coating. This increases the temperatures on the Ardurine enormously, while also greatly increasing the cave temperatures. This makes it easier for more Ardurine to form, which in turn gives the Arduroceus a bigger habitat.
People that would find Ardurine would be rather confused because of the wave-like properties that the Arduroceus living over the crystals has when it moves. It is like a snake-pit, but on the surface of the crystal, with many strands of Arduroceus moving moderately fast across the surface.

Harvesting

Harvesting Ardurine is incredible difficult for non-magic users. The heat with the caves themselves already make it super difficult to reach the crystals. Overcoming that obstacle, the Arduroceus form a sort of protective layer, making blasts pretty ineffective against the crystals. The crystals are increasibly hot, making it fire resistent and also damaging to most weapons.
By using cold magic for a prolonged period of time, could someone expel the Arduroceus. Using strong boulders could then be used to break the crystals. The next obstable is getting those super-hot pieces out of the caves into the frozen wasteland.
The Kolnai have a great need for soul gems and are the only one that know of the location of Ardurine. Using portal magic, they can extract a large portion of the cave's ambient heat by putting the other end in The Frozen North. This requires a tremendous control over the portal, because the hot air violently erupts through the portal. This trick can be most effective when there's a blizzard happening outside, so that as the pressure in the cave decreases, the wind from the blizzard can more efficiently cool down the cave and crystals. Once a cave section is cooled down enough and the Arduroceus has retreated to a warmer section within the cave, the harvesting of Ardurine can begin.

Footnotes: Etymology

While diving a bit into the world of quartz, I saw a lot of names starting with the letter A. Looking up synonyms for soul, I found the word Ardor, which has a great meaning! To not be too obvious, I changed it to Ardur and added the common "rine" suffix.

Type

Ore/Mineral