# Relationship history for MSHA mine 2400687

Current hierarchy: **Delaney Robert L → National Minerals Corp → Hecla 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:** Mining Mineral Resource Company → Hecla Mine; 1950-01-01 to 1978-12-31; source msha-controller-operator-history
- **controller_controls_mine:** Mining Mineral Resource Company → Hecla Mine; 1950-01-01 to 1978-12-31; source msha-controller-operator-history
- **controller_controls_operator:** Mining Mineral Resource Company → Mining Mineral Resource Company; 1950-01-01 to 1978-12-31; source msha-controller-operator-history
- **controller_controls_mine:** Delaney Robert L → Hecla Mine; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** National Minerals Corp → Hecla Mine; 1979-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Delaney Robert L → National Minerals Corp; 1979-01-01 to current/open; source msha-controller-operator-history