# Relationship history for MSHA mine 3000028

Current hierarchy: **Royal  Harrison → U S Slate Inc → Penrhyn Hill Slate Quarry**

- 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

- **operator_operates_mine:** Darius Slate Products Inc → Penrhyn Hill Slate Quarry; 1950-01-01 to 1985-01-03; source msha-controller-operator-history
- **controller_controls_mine:** Darius Michael N → Penrhyn Hill Slate Quarry; 1950-01-01 to 1985-01-03; source msha-controller-operator-history
- **controller_controls_operator:** Darius Michael N → Darius Slate Products Inc; 1950-01-01 to 1985-01-03; source msha-controller-operator-history
- **operator_operates_mine:** Slate Products Inc → Penrhyn Hill Slate Quarry; 1985-01-04 to 1988-04-13; source msha-controller-operator-history
- **controller_controls_mine:** Richard L  Hill → Penrhyn Hill Slate Quarry; 1985-01-04 to 1988-05-04; source msha-controller-operator-history
- **controller_controls_operator:** Richard L  Hill → Slate Products Inc; 1985-01-04 to 1988-04-13; source msha-controller-operator-history
- **operator_operates_mine:** U S Slate Inc → Penrhyn Hill Slate Quarry; 1988-04-14 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Royal  Harrison → Penrhyn Hill Slate Quarry; 1988-04-14 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Royal  Harrison → U S Slate Inc; 1988-04-14 to current/open; source msha-controller-operator-history