This seemingly innocuous item could be a real life saver in Shadowdark RPG.

The Miner’s Stone Lantern: Invented by a mage who lost his brother during a minne collapse, this ordinary looking lantern uses magic to burn everyday common stones instead of oil. This lantern appears as an everyday lantern complete with shutter but no oil reservoir. When an ordinary piece of stone is inserted into the top of the lantern, it falls in and burns as a normal lantern for one hour. Only one stone at a time may be used this way and it will be consumed completely after the hour. The stone in question can be no larger diameter than a standard silver coin.

The lantern illuminates the usual double near distance. The burning stone needs no external source of ignition- it just starts to burn when dropped in. The lantern gives off no heat and the flame does not consume oxygen.