Sparkstone

The Sparkstone emits warmth. It can keep 1ft cube worth of space warm. As an action you can cause it to emit light that casts bright light for 1 minute in a 120 foot diameter circle. You must keep holding the stone for the duration or the light will go out.

Stats found the sparkstone on a ring on the body of Velrosa Nandar and gave it to a mechanical bird in exchange for 250gp, apparently on a side quest for Bertrand B Ballswark.