Open-File Report 98-219-A
The Payette National Forest (PNF), in west-central Idaho, is geologically diverse and contains a wide variety of mineral resources. Mineral deposit types are grouped into locatable, leasable, and salable categories. The PNF has substantial past production and identified resources of locatable commodities, including gold, silver, copper, zinc, tungsten, antimony, mercury, and opal. Minor lignitic coal is the only leasable mineral resource known to be present in the PNF. Resources of salable commodities in the PNF include sand-and-gravel, basalt for crushed-rock aggregate, and minor gypsum.
Locatable mineral resources are geographically divided between eastern and western parts of the PNF. The western PNF lies west of the Riggins-to-Cascade highway (US 95 - Idaho 55), and the eastern PNF is east of that highway. The western and eastern parts of the PNF are geologically distinctive and have different types of locatable mineral deposits, so their locatable mineral resources are described separately. Within the western and eastern parts of the PNF, locatable deposit types generally are described in order of decreasing geologic age.
An expert panel delineated tracts considered geologically permissive and (or) favorable for the occurrence of undiscovered mineral deposits of types that are known to be present within or near the PNF. The panel also estimated probabilities for undiscovered deposits, and used numerical simulation, based on tonnage-grade distribution models, to derive estimates of in-situ metals contained. These estimates are summarized in terms of mean and median measures of central tendency. Most grade and tonnage distributions appear to be log-normal, with the median lower than the mean. Inasmuch as the mean is influenced by the largest deposits in the model tonnage-grade distribution, the median provides a lower measure of central tendency and a more conservative estimation of undiscovered resources.
First posted May 27, 2003
For additional information, contact:
Part or all of this report is presented in Portable Document Format (PDF). For best results viewing and printing PDF documents, it is recommended that you download the documents to your computer and open them with Adobe Reader. PDF documents opened from your browser may not display or print as intended. Download the latest version of Adobe Reader, free of charge.
Bookstrom, A. A., Johnson, B. R., Cookro, T. M., Lund, Karen, Watts, K. C., King, H. D., Kleinkopf, M. D., Pitkin, J. A., Sanchez, J. D., Causey, J. D., 2004, Potential Mineral Resources, Payette National Forest, ID. Description and Probabilistic Estimation: U. S. Geological Survey Open-File Report 98-219-A, 254 pp., https://pubs.usgs.gov/of/1998/0219a/.