# Relationship history for MSHA mine 1512421

Current hierarchy: **Kenneth L  Stacy → Southfork Coal Company → Justus Preparation 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:** Blue Diamond Coal Company → Justus Preparation Plant; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Blue Diamond Coal Company → Justus Preparation Plant; 1980-07-01 to 1992-07-30; source msha-controller-operator-history
- **controller_controls_operator:** Blue Diamond Coal Company → Blue Diamond Coal Company; 1980-07-01 to 1992-07-30; source msha-controller-operator-history
- **operator_operates_mine:** Southfork Coal Company → Justus Preparation Plant; 1992-07-31 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Kenneth L  Stacy → Justus Preparation Plant; 1992-07-31 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Kenneth L  Stacy → Southfork Coal Company; 1992-07-31 to current/open; source msha-controller-operator-history