In 3358 SD, less than twenty years before the present, a deep shaft beneath the northern Ubrik settlement of Lohva broke into a vein of liquid silver. The miners called it slick silver before they had any idea what they had found, and the name held. The strike is recorded plainly in the pit-logs of the Dnyrrak Cut, the deepest shaft in the northern field. There is nothing mysterious about where the plague came from. The Uline wrote down exactly where they cut into it.
The Dnyrrak crews were chasing a rich silver seam down past the ninth gallery, deeper than any working in living memory. What they reached was not ore. It was quicksilver that pooled and moved on its own, warm to the hand, and the pick would not bite it. The Uline are an earth-attuned people, and the wardens at the face reported the same thing the apprentices did: this far down, the dark sat close. They had cut into a shadow-seam, one of the rare places where the deep rock runs thin against the layer that carries the dead toward Malstaris. The quicksilver had stood in that draught for an age and taken it up.
Struck the silver at the ninth gallery, deeper than any cut in living memory. It runs warm and moves against the pick. The dark sits close down here. Bringing a sample to the surface. — last entry in the Dnyrrak strike-log, warden Grømgar, 3358 SD
What the silver does to a living dwarf was learned from the first to taste it. It coats the mouth, then works into the blood, and the dwarf goes out of his own body. This is not madness or fever. It is a death. The thinking self leaves as cleanly as it does on any deathbed and goes where the dead go, while the body keeps standing, breathing, and hunting, run by nothing but appetite. That is why a silvertongue cannot be reasoned with, why it eats, and why there is no cure. You cannot argue a corpse out of being dead, and you cannot call back what has already crossed over.
Lohva fell silent within the year. Bjerno went next, then the rest of the high galleries, faster than word of it could travel south. The Dnyrrak Cut was never sealed. By the time anyone understood that it should be, there was no one left in the north to do it.