Calcite boxwork from Wind Cave, southern Black Hills, western South Dakota, USA (public display, Field Museum of Natural History, Chicago, Illinois, USA).

Boxwork is a scarce cave feature characterized by a network of intersecting veins projecting from cave walls or ceilings. Boxwork veins are typically composed of calcite, but quartz and gypsum boxwork have also been reported. Wind Cave in South Dakota’s Black Hills is the best locality on Earth for seeing abundant, well-developed boxwork. Prima facie, boxwork appears to be “just” the result of differential dissolution of intensely fractured-and-veined limestone during cave formation. Research by karst workers has shown that boxwork at Wind Cave (and other localities) has a complex origin, and requires the original presence of carbonate and sulfate sedimentary rocks (see Palmer, 2007).

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