Bear Lodge Project

The REE-thorium deposits and nearby gold mineralization of the southern Bear Lodge Mountains are hosted by middle Tertiary alkaline intrusions. These thorium and REE deposits crop out throughout an area of about 16 km2 (6 mi2) (Staatz, 1983). The igneous core of the dome is microfractured and altered, thereby forming disseminated deposits. The REE and thorium mineralization precipitated within thin fractures as coatings and veinlets as much as 6 mm thick. The coatings and veinlets consist predominantly of iron and manganese oxide minerals, along with potassium feldspar and quartz. The REE and thorium are incorporated into the minerals monazite, thorite, and brockite.The Bear Lodge Project has two major components. First is the Bull Hill Mine, which includes both the Bull Hill and Whitetail Ridge deposits, as well as several identified target areas. It is located approximately 12 miles north of Sundance, Wyoming, in central Crook County. Second is the Upton Hydrometallurgical Plant (Hydromet), located 40 miles south of the Bull Hill Mine and approximately 2 miles west of the town of Upton, Wyoming, in north-central Weston County. The project consists of approximately 9,000 acres and is located on both private land and land administered by the U.S. Department of Agriculture, Forest Service - Black Hills National Forest.

The Bear Lodge Mountains were initially prospected for gold during the late nineteenth and early twentieth century. Rare earth mineralization was first discovered in 1949, and the U.S. Bureau of Mines conducted some limited exploration in the early 1950s.

In 1972, exploration was reinitiated by Duval Corporation and focused on copper/molybdenum, but it was soon determined that Bear Lodge had the potential to host an economically significant rare earth deposit. Molycorp Inc., the only domestic rare earth producer, was brought in as a partner but was not able to advance the project primarily due to weakening market fundamentals. At approximately the same time, the U.S. Geological Survey conducted field and laboratory studies and published a professional paper that concluded that the Bear Lodge area has one of the largest resources of total REE in the United States.

References

1. http://www.mindat.org/loc-7172.html

2. http://www.wsgs.wyo.gov/minerals/rare-earths

3. http://umanitoba.ca/faculties/science/geological_sciences/faculty/arc/PICTURES/Bear_Lodge-carbonatite_REE_mineralization-OGR-2015.pdf

4. https://books.google.cl/books?id=W0u7DFBMvX8C&pg=PA78&lpg=PA78&dq=bear+lodge+deposit++wyoming&source=bl&ots=_ocsjXAb0h&sig=F5U7Cla-QF1l1LkV3UVImsk-ABE&hl=ru&sa=X&ved=0ahUKEwjE5fCnkPTMAhXMk5AKHcCfDwEQ6AEIRzAF#v=onepage&q=bear%20lodge%20deposit%20%20wyoming&f=false

5. https://pubs.usgs.gov/of/2002/of02-189/of02-189.pdf

6. https://books.google.cl/books?id=PrXyCAAAQBAJ&pg=PA292&lpg=PA292&dq=USA+Stillwater++ree+deposits&source=bl&ots=liM2eVKMZM&sig=cvOWed_Ln9U8SiEomRHg2i1PCdU&hl=ru&sa=X&ved=0ahUKEwiK1Lf036jNAhXHiZAKHXN8BeMQ6AEIVTAF#v=onepage&q=USA%20Stillwater%20%20ree%20deposits&f=false

7. http://geology.com/usgs/ree-geology/

8. http://pubs.dggsalaskagov.us/webpubs/usgs/b/text/b1058a.pdf

9. https://pubs.usgs.gov/of/1995/ofr-95-0831/CHAP27.pdf