Cirrolite Core
The Cirrolite Core is a large geode of massive cirrolite crystals located in the center of Luxtia: directly below Skygrazer, parallel to the effective sea level of Luxtia. It keeps exergy closer to the point it was before The Shattering, thus protecting Luxtia from New Existence.
The core acts like a battery that "holds" the exergy at its old state. It slowly loses its "charge" over time, however. Extreme changes in exergy in the Shifting Lands can also physically damage the core, causing skyquakes.
Other Cirrolite "Cores"
Before The Shattering, 11 other similar cirrolite formations of varying sizes existed throughout the world, many larger than Luxtia's Cirrolite Core. 9 of these additional formations existed close to major population centers.
Hypothetically, any of these may have also survived The Shattering. However, none are close enough to Luxtia to be easily contacted, as the high entropy within the deeper parts of the Shifting Lands heavily distorts any information passing through it.
None of the other cores existed directly north of Luxtia.