Mountain Pass mine, California — production, ownership, and remediation timeline (1950–present)

1. Rare-earth bastnäsite deposit discovered at Mountain Pass

   Jan 1, 1949Labels: Bastn site, Clark Mountain

   • MP Materials
   • GSA Abstract
   • Wikipedia

2. Molybdenum Corporation of America acquires key claims

   Jan 1, 1950Labels: Molybdenum Corporation, Birthday claims

   • SEC Exhibit
   • GSA Abstract

3. Small-scale rare earth production begins

   Jan 1, 1952Labels: Molycorp production, concentrate production

   • SEC Exhibit
   • Wikipedia

4. Europium demand drives major expansion

   Jan 1, 1965Labels: Europium demand, plant expansion

   • SEC Exhibit
   • MP Materials

5. Company renamed Molycorp amid long production era

   Jan 1, 1974Labels: Molycorp company, light rare

   • SEC Exhibit
   • Wikipedia

6. Union Oil (Unocal) acquires Molycorp

   Jan 1, 1977Labels: Unocal ownership, Molycorp subsidiary

   • SEC Exhibit
   • Wikipedia

7. Lahontan Water Board orders cleanup after wastewater spills

   Apr 21, 1997Labels: Lahontan Water, wastewater spill

   • NPS History
   • NPS Incidents

8. Regulators prohibit pipeline and Ivanpah pond disposal

   Mar 1, 1998Labels: Regulatory ban, Ivanpah ponds

   • Lahontan Report
   • NPS History

9. County grants permit for on-site wastewater system

   Apr 6, 2000Labels: San Bernardino, wastewater permit

   • Lahontan Report

10. P-16 tailings impoundment ceases use; later permanently closed

    Jan 1, 2002Labels: P-16 impoundment, tailings closure

    • SEC Filing
    • Wikipedia

11. Chevron reactivates separation using stockpiled concentrates

    Jan 1, 2007Labels: Chevron Mining, separation restart

    • Molycorp 10 K

12. Chevron sells Mountain Pass to investor-backed Molycorp group

    Sep 30, 2008Labels: Chevron divestiture, Rare Earth

    • SEC S 1
    • Molycorp 10 K

13. Molycorp goes public to finance Mountain Pass rebuild

    Jul 29, 2010Labels: Molycorp IPO, rebuild financing

    • Wikipedia
    • SEC S 1

14. Wastewater pipeline removal and corridor remediation completed

    Jan 12, 2012Labels: Pipeline removal, corridor remediation

    • Lahontan Report

15. Molycorp declares bankruptcy; Mountain Pass operations halt

    Jun 1, 2015Labels: Molycorp bankruptcy, operations halt

    • Wikipedia
    • Forbes

16. MP Mine Operations acquires Mountain Pass out of bankruptcy

    Jul 1, 2017Labels: MP Mine, acquisition out

    • MP 2021 10
    • MP 2020 10

17. Concentrate sales resume after operational restart

    Mar 1, 2018Labels: Concentrate sales, operational restart

    • MP 2021 10

18. Stage II commissioning enables separated oxide products at Mountain Pass

    Oct 1, 2023Labels: Stage II, separated oxides

    • MP 2023 10

19. Apple deal adds recycling line planned for Mountain Pass

    Jul 15, 2025Labels: Apple partnership, recycling line

    • Apple Newsroom

20. DoD partnership funds expansion and heavy rare earth separation at Mountain Pass

    Aug 10, 2025Labels: DoD partnership, heavy rare

    • MP Release
    • DoD Release