Fulminating Gold (3.5e Equipment)
From D&D Wiki
Fulminating Gold is a precipitate of gold dissolved in aqua regia. It appears as a dark greenish powder. If crushed, heated, scratched, or otherwise damaged, the powder will explode dealing 5d6 damage in a 10 ft. radius. A Craft (alchemy) check (DC 25) can be taken to isolate the gold from the powder. A successful check requires 1 hour, and will yield a quantity of gold equivalent to 300 gold peices, and 8 ounces of aqua regia. On an unsuccessful check, roll d6. A result of 1 or 6 explodes the powder.
Fulminating Gold comes in 1 lb units. 1 lb costs 300gp. Creation of Fulminating Gold requires 300gp and 1 hour (DC 25).
This is a somewhat effective way for an alchemist to hide his gold from prying eyes.
Wikipedia: Aqua Regia