Energy startup Marathon Fusion claims to have found a scalable way to turn mercury into gold, but they still have much to prove.

Last week, Marathon Fusion, a San Francisco-based energy startup, submitted a preprint detailing an action plan for synthesizing gold particles via nuclear transmutation—essentially the process of turning one element into another by tweaking its nucleus. The paper, which has yet to undergo peer review, argues that the proposed system would offer a new revenue stream from all the new gold being produced, in addition to other economic and technological benefits.