Recent analysis of subsurface data indicates a resource containing from 0.7 to 2.5 billion metric tons of potash in the Holbrook basin of east-central Arizona, some of which underlies Petrified Forest National Park (PFNP). The potash, located many hundreds of feet underground, is present near the top of extensive bedded salt deposits of Permian age. Caverns have been leached into the salt to store liquefied petroleum gas immediately west of the PFNP. Helium was produced northeast of PFNP in the 1960s and 1970s. Solution mining would be expected to recover about 30% of the resource while conventional underground mining could recover about 70% because some parts of the deposit are not easily soluble. Total recoverable resources thus range from 210 million tons to 1.75 billion tons, assuming the entire deposit was available for development. The potash deposit is deep enough that conventional underground or solution mining would have little or no effect on the surface except for the presence of the mining facilities themselves.