This article narrates California's chemically induced second gold rush through the lens of synthetic cyanide. In coupling California's geological, environmental, and economic history to the changing nature of gold ore in the late 1880s, it explores the role that the development of cyanide leaching and the industrialization of cyanide production had on California's mining landscapes. As such, it places California as a critical node in the globalization of cyanide leaching techniques. In doing so, it links disparate geographies and histories together to explore the chemicalization of California gold mining.