# Relationship history for MSHA mine 4502531

Current hierarchy: **Rio Tinto Group → Pacific Coast Mines Inc → Excelsior Mine**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-13T11:19:05.459773+00:00

## Valid-time edges

- **operator_operates_mine:** Pacific Coast Mines Inc → Excelsior Mine; 1978-03-09 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Rio Tinto Group → Excelsior Mine; 1978-03-09 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Rio Tinto Group → Pacific Coast Mines Inc; 1978-03-09 to current/open; source msha-controller-operator-history