This stone chapel was built in 1913, when the US Army managed Yellowstone from a fort in Mammoth.
This sandstone was quarried by Scottish stonemasons from very nearby, between Mammoth and the Gardiner River. I haven’t seen the actual quarry yet.
Nearly all of the Army-era stone buildings at Mammoth were built from this sandstone.
The only exception is the Army Engineer office (below), which was built from sandstone quarried by the Montana Sandstone Company near Columbus, Montana.