- GeoRef, Copyright 2008, American Geological Institute. Reference includes data from Bibliography and Index of North American Geology, U. S. Geological Survey, Reston, VA, United States
Natural percussion cones are found on cobbles and boulders of quartzite of the Medicine Peak Quartzite (Precambrian) in Wyoming. Similar cones have been duplicated in the laboratory on cobbles of Medicine Peak Quartzite and on pieces of plate and architectural glass by impact and static loading. An analytical analysis of the forces contributing to cone formation was also made.