Historic drilling data in the Holbrook basin of east-central Arizona indicate a potash resource of 0.68 to 2.5 billion metric tons. The potash, located many hundreds of feet underground, is present near the top of extensive bedded salt deposits of Permian age. Some of this potash underlies Petrified Forest National Park (PFNP). Solution mining would be expected to recover about 30% of the resource while conventional underground mining could recover about 70%, in part because some minerals of the deposit are not readily soluble. Initial estimates of total recoverable resources range from 0.21 to 1.75 billion metric tons, assuming the entire deposit is 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.