Blackstone, known in High Gothic as noctilith, is a mysterious, black-hued, stone-like substance of unknown provenance that possesses the ability under certain conditions to outright nullify the psychic energies of the Immaterium or to absorb them and unleash them with spectacular force.
Blackstone was used by the Necrons during the War in Heaven to construct special, pylon-like devices on various worlds across the galaxy that were capable of creating tetrahedral regions of space-time immune to incursions from the Immaterium.
Blackstone's true purpose and properties remained unknown throughout Imperial history, and only at the close of the 41st Millennium did its true import become clear. Perhaps, if the Tech-priests of Mars had come to understand its significance earlier, the opening of the Great Rift could have been prevented, and the galaxy kept from plunging further toward utter calamity.
Blackstone is mined from a smooth dark rock, similar to obsidian or onyx in appearance. It registers all manner of pecularities when surveyed by Omnispex or prognost wave, and has baffled every cryptogeologist and terrastitian who has examined it.
The substance is found only on certain mineral-rich planets across the galaxy, though a close correlation has been found between worlds settled by the original Mechanicum -- the forerunners of the Adeptus Mechanicus -- and the "Quarry Worlds" upon which the mineral is present.
Some of these worlds have clearly been mined specifically for this subtance, or possibly had large monoliths of blackstone conveyed to their surface and installed there by forgotten agents from before the dawn of recorded human history.
Since the opening of the Great Rift in the Era Indomitus, the Tech-priests of the Adeptus Mechanicus have become aware of the true properties of blackstone and have sought to mine it in large quantities wherever possible. Under the direction of Archmagos Dominus Belisarius Cawl, the Mechanicus has begun blackstone mining operations across the galaxy.
This is part of an attempt to gather enough of the material for the Imperium of Man to construct its own zones of realspace stability to contain the Chaos incursions facilitated by the Great Rift. However, this quest has brought the Mechanicus into conflict with the various dynasties of the Necrons, who are also seeking to gather the resource as they did in ancient days. Like Mankind, the Necrons intend to use the blackstone to close the Great Rift and retake the galaxy for their own.
The Competition for Blackstone
The Adeptus Mechanicus has always sought to jealously protect those worlds that make up their empire within an empire. During the founding era of the Imperium, when the conquerors and lords of the Imperium sought to claim the largest and most strategically vital planets from those that could support life, the Tech-priests of the Machine God sought worlds with the most bounteous resources, such as mineral wealth, ore-rich substrates, geothermic power, or even rarer and more exotic assets.
Unfortunately, they were not the first to recognise the potential of those worlds, and there were in many instances evidence of prior mining of blackstone there tens of millions of Terran years before.
Cadia was perhaps the most famous of the worlds where blackstone was found in great measure. Before its fall, that Fortress World's wastelands were dotted with hundreds of "pylons" that had their lower portions buried below ground and their upper reaches jutting skywards.
The Cadian Pylons had strange circular holes and other smooth apertures that led to a complex maze of tunnels within them. The wind of the Cadian moorlands whistled eerily through them, producing strange harmonics that could set one on edge. Whenever the Adeptus Mechanicus sent tiny probe-Servitors to investigate and chart these tunnels, they would emerge disoriented and suffering from myriad glitches -- if they returned at all.
Just as the forces of Chaos were preparing to invade the Cadian Gate in greater numbers than ever before in 999.M41, Archmagos Belisarius Cawl of Mars theorised that there was a connection between the presence of these structures and the targets of Abaddon the Despoiler's strikes against the Imperium, the so-called Black Crusades that had scarred human history across ten Terran millennia.
It was his belief that some inherent property of blackstone, when treated and shaped correctly, reinforced the structure of the material universe, metaphysically "bracing" it against the psychic energies of Chaos and the Warp.
Blackstone structures could hold back the aetheric energy that spilled through whenever an untrained psyker was possessed by a daemon, or that poured out in great system-wrecking cataclysms from the Warp Storms that plagued the stars.
Cawl's leap of logic was a turning point for the agenda of the Martian Tech-priests. His discovery was profound -- blackstone structures could prevent empyric manifestations before they even occurred, or in other words, hold back the tides of daemons that sought to tear through the fabric of reality.
Since that day, the Archmagos has obsessively sent his agents across the galaxy to retrieve as many noctilith structures as possible. First amongst them was Magos Dominus Dentrex Ologostion. His orders were to secure the material using any means necessary -- or at the very least protect it until word could reach the Martian Priesthood and it could be harvested by the proper processes.
But there is another force in the galaxy that seeks to make use of this strange natural resource, working the stone and amplifying its inherent aura to the point it becomes a powerful shield against the intrusions of Chaos. The once-slumbering Necron Tomb Worlds, gradually awakening in the latter part of the 41st Millennium, are now populated with serried ranks of undying cybernetic warriors awakened by the Canoptek constructs that have long kept vigil over them.
The conquests that the Necron dynasties are embarking upon are merciless and terrifyingly efficient. In every Segmentum they are scouring the life from their sovereign domain with the dispassion of an Extermination Servitor burning vermin from an orbital dockyard. These are not random attacks, but carefully-planned strikes against the foundations of the Adeptus Mechanicus' galactic realm.
The Technomandrites of the ancient Necrontyr once understood how to manipulate the noctilith stone, fashioning obelisks and pylons that suppress Warp tempests and hold then back much as the Cadian Pylons once held back the Eye of Terror. Yet the Technomandrite Crypteks who pioneered this process as mortals of flesh are only now fully awakening, and many have badly damaged memory engrams -- even those relatively intact have neither the numbers nor the influence to effect works of galactic engineering.
For their part, the Tech-priests of the Adeptus Mechanicus do not yet fully understand how to utilise blackstone, but they do have an unparalleled mastery over the macro-industry of the Imperium of Man. With the teeming flock of the Machine God harnessed by the same masters, the mining and distribution of noctilith pylons and obelisks could be achieved on a galaxy-wide scale.
Together, the two forces could perhaps restore order and logic to realspace. Yet though the Forge Worlds and the Necron dynasties have found common cause before, they are so consumed by their own sense of superiority that they would never truly work in concert. Instead the one concentrates on bringing about the demise of the other by the most violent and final methods that they can conceive.
The arcane geniuses of the Necrons now lead phalanxes of metal warriors and insectoid Canoptek constructs against the scions of the Machine God on a hundred mineral-rich worlds. Soon after Magos Ologostion made his first play to gain blackstone upon the world of Amontep II, the Technomandrite Cryptek Agdahax of the Sautekh Dynasty rose to stop him. In the Necron Cryptek's eyes, humanity unwittingly seeks the most valuable of resources in the galaxy, and it is high time such mortals learned their place in the true order of things.
Battle of Vorlese
The forces of Chaos also recognised the potential power of blackstone and arcane weapons derived from it. The Despoiler's seizure of Cadia during the 13th Black Crusade in 999.M41 had finally destroyed its great blackstone pylons, allowing the Eye of Terror to spill at last from its boundaries and infect half the galaxy as part of the Great Rift.
Only splinters of those original sentinels were recovered, mere fragments of the occult nexus of pylons that had once existed to contain the tides of the Warp and create what had been the Cadian Gate.
Those fragments of the original pylons were taken from the remains of Cadia by the minions of Chaos, tempered on dark forges, bound by fell sorceries and augmented in blood-soaked rites until their original power was twisted such that they became weapons capable of disrupting the flow of the Immaterium.
Just one such shard was now capable of extinguishing the Warp's touch from an entire star system. And if that system lay at the centre of a Warp conduit, a passageway through the Warp used by starships for easy navigation, then the conduit was lost too. This ability allowed the servants of the Dark Gods to use these shards to direct the flows of voidship traffic through the Warp to where and when they desired.
This was a potent new weapon in the post-Great Rift era, and was used to try and prevent Roboute Guilliman's Indomitus Crusade from reaching the wider galaxy from Terra by blocking all the Warp egress roots from the Imperial Throneworld. Only the actions of the Sisters of Silence and the Adeptus Custodes, soon to be free to go out into the galaxy once more, prevented the jaws of this trap from being sprung at the Battle of Vorlese.
The Obsidian Circlet
A dark, glassy substance was found by the Drukhari of Commorragh during raids on worlds held by both Necrons and the Adeptus Mechanicus. Within the Haemonculus Covens of the undercity of Commorragh, it was not long before those ancient Dark Eldar discovered that this material could be used to repel daemonic entities.
After more raids were launched against Necron and Adeptus Mechanicus planets, the plundered blackstone was arrayed around the ever-deepening Chasm of Woe in what became known as the "Obsidian Circlet." The Circlet helps to seal off the sunken sub-realm of the Dark City created following the eruption of daemonic legions into Commorragh from Khaine's Gate just before the birth of the Great Rift. The captives from these raids are also sent into the Chasm, where their anguished deaths nourish the black souls of the Drukhari.
Significance of Blackstone
Some amongst the higher orders of the Tech-priests call noctilith the "Pariah Stone," believing the mineral is a physical incarnation of the Null gene that lends the Culexus Assassins and the Sisters of Silence their unsettling soulessness and potent anti-psyker abilities. Others maintain it is stone mined from within cosmic singularities, and that it originates from another dimension all together.
The most abiding of the numerous theories concerning the nature of blackstone is that it somehow resonates with the psychic energies of the Immaterium and, if correctly machined, can even manipulate the raw energy of Chaos.
Belisarius Cawl's Theory of Empyric Polarity posits that blackstone is not inherently possessed of Chaos energy, nor is it anathema to it. However, much like ferrite metal can be polarised to bear a magnetic charge, blackstone can be charged under the right circumstances to interact with the metaphysical energies of the Warp.
The monoliths of blackstone that formed the Cadian Pylons, the obsidian slabs found inside the wreckage of the Gates of Kromarch, and the Eldritch Needles of Nemesis Tessera -- all these are thought to have been negatively charged, and hence able to hold back the the encroachment of the Warp upon their respective world's locations.
The Blackstone Fortresses captured by Abaddon the Despoiler during the Gothic War are thought to be positively charged with empyric energy, and hence are extremely destructive machines of war that can discharge beams of Chaos essence if correctly weaponised by one who knows their secrets.
If this theory has even a grain of truth to it, then blackstone could theoretically be used to shore up the invisible barriers between realspace and the nightmare realm of the Warp, quarantining the Cicatrix Maledictum that now cuts the galaxy in half and perhaps even sealing it forever.
- Codex: Drukhari (8th Edition), pg. 47
- The 13th Black Crusade (Background Book), pp. 14-15
- Warhammer 40,000: Forgebane (Boxed Set Book), pp. 2-3, 9, 13
- Watchers of the Throne: The Emperor's Legion (Novel) by Chris Wraight, Ch. 29