Phenalope

Phenalope, also known as rhodonite, was related to the less valuable rhodochrosite.

Description
These pink to rose-red semi-precious stones could be facet-cut or tumbled smooth. It was found in crystal form or in large non-crystalline deposits that were cut in slabs, then broken into smaller pieces for tumbling. Folklore said this stone would protect against magical fire. A typical specimen had a base value of 50 gp.

The stone's rough texture was the attraction for some. Such people wore phenalopes as a symbol of their tenacious nature.

Powers
Folklore was correct. Phenalope extinguished magical flames within a 60 ft (18.3 m) radius and prevented them from igniting or re-igniting. A fireball would only produce a flash of light and a puff of smoke around the surface of the sphere where the fireball would have detonated. Non-magical fires were also suppressed within range of this stone. No fires could be lit and existing fires had a good chance of being extinguished. Oil-based fires were somewhat less susceptible to phenalope, but eventually they would succumb also. Because of this property, phenalope was used as an inlay in the floors of large meeting halls, ballrooms, and other such places. Phenalope was effective in extinguishing the magical flame generated by mellochrysos.