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Recently, it has been shown that it is possible to apply liquid-phase exfoliation to non-layered materials, yielding quasi-2D nanosheets. It has been proposed that even a slight bonding anisotropy in the starting crystal will lead to a platelet-like geometry, albeit with low aspect ratio. While this development opens the way to many previously unexplored 2D materials, a particularly interesting class of crystals for exfoliation are natural-occurring mineral ores due to their diversity and abundance. Here we describe the liquid-phase exfoliation of the natural mineral, pyrite, also known as fool’s gold. The exfoliation process yields highly crystalline, low aspect ratio nanosheets with stoichiometry FeS₂, with all impurity and non-platelet material removed during a two-step centrifugation protocol. These 2D pyrite flakes can be fabricated into lithium-ion battery anodes which show remarkable capacities of >1200 mAh g⁻¹.