Since its advent at the end of the nineteenth century, cyanide processing facilitated the intensification and global expansion of industrial gold mining. Today, there are important indications that artisanal and small-scale gold mining (ASGM) is on the verge of a similar cyanide revolution: while ASGM is typically associated with mercury-based processing, mercury amalgamation is increasingly replaced with, or complemented by, cyanidation. Relying on evidence from the Philippines, Indonesia, and Burkina Faso, we demonstrate how this transition is having a deeply transformative impact on ASGM communities. On the one hand, cyanidation produces clear efficiency gains. Together with rising gold prices, it is fueling a dramatic expansion of ASGM by enabling the profitable extraction of lower-grade gold deposits. On the other hand, it contributes to the emergence of new and often highly unequal labor and revenue-sharing arrangements. More broadly, these findings demonstrate the highly uneven impact of socio-technical transformations. Consequently, the growing number of efforts to intervene in the technological make-up of ASGM, usually in the name of efficiency and sustainability, should be wary of having unintended consequences.