Refined Stonerust

Stonerust can be refined by apply steady pressure while the ore is subjected to magical heat. Both heat and pressure need to be applied slowly and starting low. As the heat and pressure increase, the impurities literally fall away from the Stonerust resulting in a much purer pellet which is much more powerful. Once the Stonerust is refined to a sufficient degree, it's less reactive to heat but still ignites and then explodes on impact. It's still not a good idea to store the refined Stonerust near open flames or in hot places but its less likely to ignite than its unrefined state. Once refined Stonerust can be broken into smaller pieces through strong constant pressure, not sharp force which will ignite it.
Once refined, a pellet the size of a pea can propel a quarter sized bullet hundreds of feet very very quickly, but it also makes a distinctive pop noise that can be heard roughly 50 feet away.
A single pellet is worth 5 silver and can fire a single shot. Each pellet weighs about the same as the bullet but is smaller, both weigh about 30 grams or 1/20th of a pound. A pound of refined Stonerust is 10-20 gold