# Relationship history for MSHA mine 1508037

Current hierarchy: **Cyprus Amax Minerals Company → Buckhorn Processing → No 2 Prep Plant**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **controller_controls_mine:** Mountain Coals Inc → No 2 Prep Plant; 1974-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Buckhorn Mining Corp → No 2 Prep Plant; 1975-01-01 to 1981-09-14; source msha-controller-operator-history
- **controller_controls_operator:** Mountain Coals Inc → Buckhorn Mining Corp; 1975-01-01 to 1981-09-14; source msha-controller-operator-history
- **operator_operates_mine:** Buckhorn Processing → No 2 Prep Plant; 1981-09-15 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Cyprus Amax Minerals Company → No 2 Prep Plant; 1981-09-15 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Cyprus Amax Minerals Company → Buckhorn Processing; 1981-09-15 to current/open; source msha-controller-operator-history