This paper provides the first detailed characterisation of the interface dynamics between artisanal and small-scale mining (ASM) and large-scale mining (LSM) activities in Papua New Guinea, recently termed 'ASM-LSM interfaces'. We characterise these interfaces across the project lifecycle at operational, non-operating, and future mines. Despite industry commitment to contemporary standards for social responsibility, our study shows that large-scale miners actively co-construct ASM-LSM interfaces and contribute to their intensification, which often results in violence, dispossession, and entrenched inequalities. By focussing on interfaces, we identify the influences and effects on the underlying elements that small and large-scale mining activities have in common, namely land, labour and capital. This provides the basis to chart the 'mining encounters' among the host of actors entangled in these extractive zones, and the competing interests that arise at each resource conjuncture.