Once you've unearthed it, you open it carefully. Sudden brightness illuminates the ground around you. True, the light coming from the chest isn't actually all that bright, but after wandering around in the dark for hours, it completely messes up your vision.
The chest is filled with golden runes, glowing faintly. Take them with you; you've earn them. Oh and know this... Decoding their secret message just might prove helpful.

Just a little further now...