The following is declared Open Game Content:
Found only rarely in veins of iron ore mined from the craters of long-dormant volcanoes, gladstones are naturally occurring, glossy, metallic, jet pebbles of incredible denseness. A single gladstone weighs as much as 10 gp, even though it is no larger than a dwarf's thumbnail.
If ingested, the gladstone will bring the user an overwhelming feeling of euphoria and contentedness that lasts 1d8 days and imparts a permanent +3 to the swallower's CON. However, if the user swallows more than two gladstones during his or her lifetime, the user must Save vs. Disease or be stricken with uncurable anemia, resulting in a permanent -6 to CON.
Gladstones may be used as ammunition in slings and slingshots, and when used as such, impart a +3 against ghouls, ghasts, and zombies. They may be retrieved from corpses and re-used. However, with every use in this manner, there is a 25% chance the gladstone will explode on impact and be unretrievable.
A gladstone's true magical power, and the reason they are treasured by dwarves, is that a single gladstone mounted on the end of an oaken staff may be used to find potable water with only a 5% chance of failure.