# Relationship history for MSHA mine 4602531

Current hierarchy: **Heidelberg Materials AG → Hanson Aggregates Pma Inc → IRON CITY 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

- **operator_operates_mine:** Standard Aggregates Inc → IRON CITY PLANT; 1950-01-01 to 1989-09-30; source msha-controller-operator-history
- **controller_controls_mine:** Standard Slag Company → IRON CITY PLANT; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Standard Slag Company → Standard Aggregates Inc; 1950-01-01 to 1989-09-30; source msha-controller-operator-history
- **controller_controls_mine:** Lafarge S A → IRON CITY PLANT; 1987-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Pioneer International Ltd → IRON CITY PLANT; 1989-01-16 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Lafarge Construction Materials → IRON CITY PLANT; 1989-10-01 to 1996-05-15; source msha-controller-operator-history
- **controller_controls_operator:** Lafarge S A → Lafarge Construction Materials; 1989-10-01 to 1996-05-15; source msha-controller-operator-history
- **operator_operates_mine:** Pioneer Mid-Atlantic Inc → IRON CITY PLANT; 1996-05-16 to 2000-08-03; source msha-controller-operator-history
- **controller_controls_operator:** Pioneer International Ltd → Pioneer Mid-Atlantic Inc; 1996-05-16 to 2000-08-03; source msha-controller-operator-history
- **operator_operates_mine:** Hanson Aggregates Pma Inc → IRON CITY PLANT; 2000-08-04 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Hanson PLC → IRON CITY PLANT; 2000-08-04 to 2007-08-22; source msha-controller-operator-history
- **controller_controls_operator:** Hanson PLC → Hanson Aggregates Pma Inc; 2000-08-04 to 2007-08-22; source msha-controller-operator-history
- **controller_controls_mine:** Heidelberg Materials AG → IRON CITY PLANT; 2007-08-23 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Heidelberg Materials AG → Hanson Aggregates Pma Inc; 2007-08-23 to current/open; source msha-controller-operator-history