Artisanal and small-scale mining is an important livelihood activity in many biodiversity hotspots. There is substantial international concern about the negative impact of artisanal and small-scale mining on biodiversity, yet in most places this remains poorly understood. We explore the impacts of a high-profile mining rush: the 2016 sapphire rush at Bemainty, Eastern Madagascar, where tens of thousands of miners descended on a protected forest. Media coverage claimed the rush caused hundreds of hectares of deforestation and threatened lemur populations. Using the synthetic control method to estimate counterfactual outcomes, we find no evidence that mining increased forest loss or degradation. Supported by informal interviews and a lemur survey, we argue that mining at Bemainty had limited impacts on the surrounding forest, relative to other threats. Our results highlight the heterogeneity of environmental impacts from artisanal and small-scale mining and emphasize the need for more robust evaluations to inform context-specific policies.