Thunderstone

A Thunderstone is a rock with carvings on it that makes a loud booming noise when it is struck with a hard blow or against a surface, e.g. because it has been thrown. The noise might deafen weak creatures that are close to the source of the boom. The rock weighs 1 lb. and is quite expensive, costing 30 gp, but is one of the few reusable alchemic substances, along with fleshgems, plaster casts, and alchemical silver, that are infinitely reusable.

Thunderstone

Les Amis Improbable Rondor