GEOCHEMICAL RECONNAISSANCE OF CRITICAL MINERALS FROM THE WESTERN PHOSPHATE FIELD OF IDAHO, WYOMING, UTAH, AND MONTANA

The objective of this project, funded by the USGS Earth MRI Initiative, is to gather new geochemical data on critical minerals (CMs) associated with sedimentary phosphate deposits of the Western Phosphate Field (WPF). The WPF covers an area of 300,000 square kilometers across Idaho, Utah, Wyoming, and Montana, and is known to be one of the world's largest commercial sources of phosphate (Jasinski and others, 2004). Phosphate from this region has been mined since the early 1900s, primarily for the fertilizer industry, and current annual production exceeds 5 million tons. While the primary purpose of mining in this region is for phosphorus extraction, previous research has indicated that these phosphate deposits also contain elevated levels of rare earth elements (REEs) and other critical minerals, including chromium, vanadium, and fluorine, particularly within the Meade Peak and Retort members of the Permian Phosphoria Formation (Piper and others, 2007, Emsbo and others, 2015). This project focuses on studying these specific units and their associated phosphorites and organic-rich mudstones to understand the factors contributing to the enrichment of CMs, including REEs.

Specific activities of this project which is a four-state cooperative effort, involving the Idaho Geological Survey, Wyoming State Geological Survey, Utah Geological Survey, and Montana Bureau of Mines and Geology include: 1, Documenting the chemistry, sedimentology, and stratigraphy of zones enriched with critical minerals within the Meade Peak and Retort members of the Permian Phosphoria Formation. and, 2, Investigating the chemical and physical processes responsible for the formation and concentration of CMs and REEs in the targeted areas that will contribute to the development of exploration models and resource maps. The significance of this project lies in the potential to exploit the vast resources of CMs, such as REEs, vanadium, and fluorine, as byproducts of the existing phosphate mining and processing infrastructure in the region. The estimated potential byproduct REE production from the Western Phosphate Field is substantial, with the capacity to meet approximately one-third of the current US demand for REEs (Emsbo and others, 2016).