Black ice

Black ice was a mineral found throughout a few areas of the Frozenfar in northwest Faerûn. It was magical in nature, having been permeated with the evil quintessence of the monolith known as the Cryshal-Tirith.

History
The destruction of Cryshal-Tirith in the mid–14 century DR did not end the evil corruption of the artifact known as Crenshinibon. Rather, a remnant of the power formed black ice beneath the ice at the site of its destruction.

The substance was discovered by the the dwarven stone-carver Baerick Hammerstone, some time before the, while being influenced by the undead Akar Kessell. After some time, Hammerstone and his dwarves managed to mine out hundreds of pounds of the black mineral.

Around the same time, the Ice Witch of the North either discovered, or built herself, an entire tower made of black ice.

Properties
Black ice was extremely resilient, and able to withstand the swing of a pick ax made by an experienced miner.

In addition, black ice exuded a malevolent influence over those that kept it within their possession. Over time it corrupted their spirits.

Applications
When heated, black ice could be shaped and carved for use in crafting jewelry, armor, and even weapons.

Baerick Hammerstone carried a maul and wore a suit of armor that were each crafted in part from black ice.