Chardalyn

A chardalyn was a rare, naturally occurring substance mined in nugget form in the northern and northwestern regions of Faerûn.

Description
When first discovered in Netheril, these black stones   were described as "useless rocks" by miners, but their affinity for magic was soon discovered. These nuggets were as brittle as glass and turned into a powder when they were forcefully struck or when hurled against a solid object. Until the early 1370s DR, the rarity and fragility of chardalyns contributed to their high base value of 20,000 gp. Once techniques like gem magic became more widespread, the base value of chardalyns dropped to 8,000 gp for a large stone that could hold the most powerful magics, and even lower for smaller, more limited stones.

Powers
A single chardalyn could absorb one spell, which was released when the stone was crushed or destroyed. This was a natural ability of the substance and did not require any magical preparation or treatment beforehand. The spell stayed encased in the chardalyn indefinitely&mdash;it could be released seconds or centuries later. Usually, the spell was cast with the chardalyn as the target and it was absorbed without fail, but an empty chardalyn had a slightly better than even chance to absorb a spell that did not target it directly, as long as it was in the spell's area of effect. Once a chardalyn was imbued with a spell, additional spells had no effect on the stone. When shattered, the attributes (power, volume, duration, damage, etc.) of the spell were unchanged and the focal point was the exact location where the breakage occurred.

The ancient Netherese tried for many years to find a use for the powder residue left behind after smashing a chardalyn, but to no avail.

The epic arcanist spell Mavin's earthfast required six chardalyn imbued with transmute mud to rock spells as one of its material components.

History
These magical stones were first discovered (by humans) in ancient Netheril near the city of Fluvion, where the Wont Surge joined the Zweihaus River, in −1205 DR (NY 2654) by an arcanist named Elorian. Miners brought her what they considered useless rocks, but she sensed they were magical and soon discovered their capacity for spell storage and release. This tremendous discovery brought immediate prosperity to Fluvion and ushered in what historians called the Age of Discovery that lasted for over half a millennium. After the Fall of Netheril, Fluvion was just a ruin on the Plain of Standing Stones.

Chardalyn were known to the Sarrukh millennia before the Netherese discovered them. A vast cache of chardalyn stones, long forgotten by all but the incredibly ancient Terraseer (a sarrukh lich from Isstosseffifil who visited the Netherese in disguise), was buried deep below the foothills north of the Sword Mountains near the Sword Coast. In −2368 DR (NY 1491), the Terraseer manipulated the Netherese to build an outpost there and dig a well that would never run dry. In the process of this expedition, the Netherese army had to kill thousands of owlbears and other monsters, eventually slaying the deepspawn that guarded the lost chamber. The Terraseer got his chardalyns, but the outpost, Quesseer, lasted less than 300 years and only the Old Owl Well was left.