Lumenpetrium is a corruption of Lumen Petra, which (if Google Translate is anything to go by) is Latin for 'glimmer rock'.
This is important because?
I have long envisioned there being a special mineral in the Frozen Skies setting that could be used for possible plot ideas (i.e. the 'spikes' mentioned in Alyeskan Tales) and to provide some justification for the Weird Science Arcane Background. Effectively think of it being Alyeska's counterpart of either Ghost Rock or Warpstones.
Now Lumenpetrium (or Glimmer Rock as it's commonly called due to how it sorta shines in the light) has some residual energy until 'charged' via an alchemical process. This process typically uses electricity to effectively create a battery to power Weird Science devices. The Sodkans (when they still had their great empire) discovered a large deposit of Glimmer Rock, which they kept a fiercely guarded secret, and an alternative of 'powering' the rocks; Souls.
The so-called 'Sodkan Method' (least to those who know of it) was discovered literally by accident when a lab experiment went disastrously wrong. A team of Sodkan scientists were trying to increase the power load of Glimmer Rock when an equipment malfunction resulted in a power overload and an explosion that killed most of the team and severely injured many others. Curiously the sample piece of Glimmer Rock was still intact and hadn't suffered any damage, though it now emitted a sickly green glow and faces of those who'd been killed in the accident could be seen in the rock. Many tests were run, using criminals who'd been sentenced to death, until the Sodkan Method of using souls was proven and then refined to be more efficient. Not long after this, the Sodkans greatly expanded their mining colony in Alyeska.
The onset of the Great Darmonican War greatly hampered the Sodkan Glimmer Rock Project, the condemned criminals it'd been using were instead being sent to the front lines to fight in penal battalions. In addition the Project had great demands placed upon it by the Sodkan Empress herself to produce weapons for the war effort, forcing the Project scientists to take drastic measures to keep up production of the 'Sodkan Refined Rocks'. Late in the war the Project did start to bear some fruit by producing the so-called 'Tin Men', mechanical automatons that were used to replace the Project's diminished work force of miners. Militarized versions were starting to reach the prototype stage a large explosion destroyed the Sodkans' main research base and devastated the surrounding area during a visit by the Sodkan Empress, the double blow effectively ended the Holy Empire's chances of winning the war and ultimately ended the War itself. In the aftermath the Holy Empire shattered, giving rise to the Union of Sodkan Republics and the Iron Collective.
The Blast had other far-reaching effects; The area devastated by the explosion remains a dead zone that effectively separates the Iron Collective from the Union of Sodkan Republics. There are also the Spikes, where streams of Glimmer Rock have started building up energy on their won accord before discharging it in a burst of electricity. These discharges of energy have yet to inflict anything more than some minor damage, though they have been growing in regularity.
There are rumours that the Iron Collective may have restarted the old Sodkan Project, though this can only bring bad tidings for Darmonica's future.