Voidstone is a psi-active mineral capable of negating empathic signals.

Empaths are not physically harmed by voidstone, but find the experience of being within its field of effect to be disorienting. When exposed to voidstone for long periods, they begin experiencing symptoms analogous to sensory deprivation, experiencing hallucinatory empathic sensations that have no actual source. Sapient empaths may feel the area to be inhabited by some genius loci or other unseen spirit or ghost, and most Avishraan cultures, of any species, tend to attach supernatural importance to voidstone as a result, usually with some negative aspect.

When encountered in quantities large enough to be seen, voidstone is a mineral of a very dark gray color, just short of being black; its surfaces tend to be smooth, but matte rather than glossy.

Voidstone is famously durable, being very resistant both to impact and to chemical weathering, and has a high melting point; it is a difficult material to work or shape, and is most often used as-is (if at all).

Pieces of voidstone also have the property of preventing empathic signals from passing within or through a volume linked to their shape and mass.

Voidstone does not readily chemically combine with other substances in nature. While it is often present in other minerals as scattered grains, in this unconcentrated state it has no discernible anempathic effect and, in fact, usually goes unnoticed. Since voidstone's usefulness comes from concentration rather than dilution, there is generally little benefit from using it as a component in any other material.

Voidstone is found is trace amounts throughout Avishraa's crust and mantle, generally in concentrations too low to be detectable, but can very rarely be found in relatively pure deposits, usually associated with igneous rocks.

The sophont species of Avishraa have known of voidstone since prehistoric times, and their relationship with it has changed remarkably little since then. While it has its uses, its rarity, its inconvenient physical properties, and above all its indiscriminate effect on all empaths, tend to enforce a certain reluctance to resort to it.