Fire opal

Fire opal was a rare gem stone usually found near hot springs and geysers.

Description
Fire opal was a brilliant orange-red form of opal that was usually solid in color but could have golden or greenish flashes. A typical specimen had a base value of 1,000 gp.

Powers
They were the favored gems to use in helms of brilliance. Their affinity for igniting, releasing, and controlling fire made them useful in formulating inks to inscribe scrolls, enchanting immersions for making items, and mounting on devices as a focal point of discharge.