Sol Stone

A shining piece of obsidian floating just above the ground.

Sol stones are valuables with negative volume and mass, making your load lighter just by being in your inventory. A natural onyx sol stone has a mass of negative 1000g, but it is possible to use a scroll of change material to change it into a negative volume of some very dense material, creating a larger negative mass and reducing inventory weight even further. Sol stones can be stored in a container to reduce its weight, but they do not add room to a filled container.

Wielding an item with negative mass has very strange effects.

Originally being impemented in the CLIVAN variant, they were ported back into vanilla in 0.50.9 release.