# Relationship history for MSHA mine 2901872

Current hierarchy: **Westmoreland Mining Holdings LLC → San Juan Coal Company → Black Diamond 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

- **controller_controls_mine:** BHP Billiton → Black Diamond Mine; 1984-04-02 to 2016-01-31; source msha-controller-operator-history
- **operator_operates_mine:** San Juan Coal Company → Black Diamond Mine; 1998-10-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** BHP Billiton → San Juan Coal Company; 1998-10-01 to 2016-01-31; source msha-controller-operator-history
- **controller_controls_mine:** Westmoreland Coal Company → Black Diamond Mine; 2016-02-01 to 2019-03-14; source msha-controller-operator-history
- **controller_controls_operator:** Westmoreland Coal Company → San Juan Coal Company; 2016-02-01 to 2019-03-14; source msha-controller-operator-history
- **controller_controls_mine:** Westmoreland Mining Holdings LLC → Black Diamond Mine; 2019-03-15 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Westmoreland Mining Holdings LLC → San Juan Coal Company; 2019-03-15 to current/open; source msha-controller-operator-history