Largest Copper Deposits in the United States: Top 5 Mines

The United States hosts several world-class copper deposits, primarily in the Southwest. Here are the five largest by reserves and production:

1. Bingham Canyon Mine (Kennecott) – Utah

• Location: Oquirrh Mountains, 20 miles SW of Salt Lake City.
• Status: World's largest man-made excavation (open pit); ~17+ million tons Cu reserves.
• Operator: Rio Tinto (Kennecott Utah Copper).
• By-products: Gold, silver, molybdenum.

2. Morenci Mine – Arizona

• Location: Greenlee County, ~100 miles NE of Tucson.
• Status: Largest copper producer in North America; ~750,000 tons Cu/year.
• Operator: Freeport-McMoRan (72%) / Sumitomo (28%).
• Type: Four open pits + underground.

3. Butte Mining District (Continental Pit) – Montana

• Location: Butte, Montana.
• Status: Historic district; >10 million tons Cu produced since 1880s. Active open-pit mining resumed.
• Operator: Montana Resources.
• Note: Also major molybdenum, silver.

4. San Manuel Mine (now part of Safford) – Arizona

• Location: Pinal County, ~100 miles NE of Tucson.
• Status: Formerly large underground block-cave; transitioned to open-pit (Safford Mine). ~500,000 tons Cu/year combined.
• Operator: Freeport-McMoRan.

5. Climax Mine – Colorado

• Location: Sawatch Range, near Leadville (highest elevation mine in US, ~11,300 ft).
• Status: World's largest molybdenum deposit; significant copper by-product.
• Operator: Freeport-McMoRan (Climax Molybdenum Co.).

Geological Context

These are predominantly porphyry copper deposits—large, low-grade (0.3–0.7% Cu) but high-tonnage bodies associated with Mesozoic to Tertiary intrusive complexes in the Cordilleran magmatic arc. The US holds ~6% of global copper reserves; Arizona alone produces ~70% of US copper.