Critical commodity studies, Stillwater Complex, Montana and Duluth Complex, Minnesota Completed

Science Issue and Relevance

The platinum-group elements (PGE) are consistently identified as critical minerals for many nations, including the United States, with the only primary bedrock PGE deposit in the U.S. being the J-M Reef in the Stillwater Complex, Montana. Scientific research can make our resource assessments of critical minerals more effective. For example, we can study representative deposit types in order to understand what we should be looking for and how we should look for them. Using this information, we can build the scientific databases we need to conduct geologically based assessments and identify gaps in our knowledge. Occasionally, new, provocative research suggests our paradigms may be incorrect and calls for us to go into the field to test ideas. Although the J-M Reef has been mined since 1986, very little quantitative rock geochemistry has been published.

Methodology to Address Issue

The last resource assessment of the Stillwater Complex (Zientek, 1993) was conducted over 20 years ago, just after the Stillwater PGE mine went into production. Our project will conduct the following tasks to make resource assessments of critical minerals more effective: 

• Update map database from the last resource assessment (over 20 years ago) for the Stillwater Complex,
• Test and apply new mapping and analysis techniques for mafic and ultramafic layered intrusions,
• Conduct a comparative study between contact-type deposits in Stillwater and those at Duluth (Midcontinent region), and
• Summarize and publish the USGS data on the J-M Reef.