It doesn't give gold.

Go to Items, click 'My Items' (remaining on the 'Treasure' tab). You will now see a treasure chest there you should open for goodies.

Note: If you only have one of a chest, opening it will cause what it contained to scroll by above. If you open more than one at a time it will bring up a dialogue box with a list of all contents received that you close when you are ready - giving you a chance to understand what you received.