Field ReportMoffat County, Colorado

Mineral Exploration.

The West Side Placer: a gold and rare-earth heavy-mineral-sand project in the high sage country of northwest Colorado. Discovered in 1894, examined by a century of engineers, revived in the 1980s — and now the subject of a modern critical-minerals program built on ten years of fieldwork, four independent laboratories, and a federal research grant.

Operated by AuPt Industries LLC. Commercial terms and valuations are not published; history, geology, and methods are.

Contents

  1. 01The West Side PlacerA gold and rare-earth placer field in the high sage country of Moffat County, Colorado — discovered in 1894, worked in three eras, and now the subject of a modern critical-minerals program.3 min read
  2. 02A Field Discovered: 1894A prospector named Adams finds gold in the terraces in 1894; within a year, eastern investors are building a 36-mile canal across the sage to wash it — one of the boldest placer gambles of its era.3 min read
  3. 03The Hoover FileBetween the 1890s failure and the 1980s revival, the district drew a string of serious engineering examinations — including a file in the Colorado School of Mines special collections connecting the ground to Herbert Hoover.3 min read
  4. 04The 1980s RevivalCentennial Gold and Marathon return to the field with modern gravity equipment, produce roughly nine hundred ounces in a season, and field an approach from a French chemical giant about the monazite — before the gold price ends the program.3 min read
  5. 05Geology of the TerracesPliocene–Pleistocene river terraces blanket the district in ten to forty feet of gravel — heavy-mineral sands shed from Archean granite highlands and concentrated by millions of years of shifting rivers.3 min read
  6. 06Rare Earths in the Black SandMonazite makes up a quarter to a third of the heavy-mineral fraction — an order of magnitude above the placers that fed America's historic rare-earth supply — with a neodymium-praseodymium-rich profile aimed at the magnet supply chain.3 min read
  7. 07Proving the GroundA decade of fieldwork in sequence: district reconnaissance in 2014, permitted bulk sampling from 2016, drilling, and an assay program spread deliberately across independent laboratories so no single result could flatter the project.3 min read
  8. 08Clay, the King's ThiefKaolinite clay coats the gold, armors the gravel, and steals fines from every careless circuit — the single variable that has governed recovery on this field since 1895, and how the modern flowsheet finally deals with it.3 min read
  9. 09Permits, Water, and ReclamationThe unglamorous record that makes everything else possible: state mineral leases, limited-impact and hardrock permits, BLM claims maintenance, water rights, posted reclamation bonds — and a low-impact operating ethos suited to a working landscape.3 min read
  10. 10The DOE Grant and What Comes NextThe project joins the Department of Energy's CORE-CM critical-minerals initiative for the Green River Basin — a coalition with academic partners to assess the basin's rare-earth sands — and the data library becomes the founding use case for an AI platform.3 min read