With an effort you are able to get the box out of the coffin without disturbing the bones. To your delight, it contains 275 gold pieces and 14 gems worth 20 to 120 gold pieces each. [For each gem roll 2D6 and multiply by 10.] There are also three healing potions that will heal 6 points of damage each. This is more loot than you ever expected to find in an Old Dwarf Mine.
You may use the healing potions right now if you wish, or save them for later and use them at any time you are not in combat. Note which characters carry them.
With this much treasure, it suddenly seems like a good idea to get out of the mine. Or if you wish to keep adventuring you can return to the intersection and make a different choice.