Boxwork
From Wikipedia, the free encyclopedia
Boxwork is a speleothem composed of thin blades of the mineral calcite that project from cave walls and ceilings, forming a honeycomb pattern. The fins intersect one another at various angles, forming "boxes" on all cave surfaces. Some of the most extensive boxwork deposits in the worlds are found in Wind Cave National Park in South Dakota.
The origin of boxwork remains a mystery at Wind Cave. Recent research suggests that the boxwork fins once filled cracks in the rock long before Wind Cave formed. As the walls of the cave began to dissolve away, the vein and crack fillings did not, or at least dissolved at a slower rate than the surrounding rock, leaving the calcite fins projecting from the cave surfaces. The dissolution was likely accomplished by water that flowed very slowly through the cave. The water became saturated with calcium carbonate quickly, but remained unsaturated with magnesium carbonate (the dolomite). Thus as the water moved through the cave it dissolved the dolomite, surrounding the boxwork fins, but was unable to dissolve the boxwork, leaving it projecting into the cave rooms.
