Hydrothermal sediment deposits from the Goose Lake (Yellowstone) sediment core

Hydrothermal sediment deposits from the Goose Lake sediment core, Lower Geyser Basin, Yellowstone National Park. The orange sediment (left, scale in cm) consists mostly of fluorite, a common mineral in some hydrothermal deposits, but not usually found in lake sediments. A scanning electron photomicrograph (right, scale in μm) shows diatoms entombed in a matrix of tiny fluorite spheres. Photos by Christopher Schiller, 2018.