# Relationship history for MSHA mine 1800001

Current hierarchy: **Heidelberg Materials AG → Essroc Cement → ESSROC**

- 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:** Alpha Portland Cement Company → ESSROC; 1950-01-01 to 1982-11-17; source msha-controller-operator-history
- **controller_controls_mine:** Alpha Portland Industries Inc → ESSROC; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Alpha Portland Industries Inc → Alpha Portland Cement Company; 1950-01-01 to 1982-11-17; source msha-controller-operator-history
- **controller_controls_mine:** Italcementi Spa → ESSROC; 1950-01-01 to 2016-10-11; source msha-controller-operator-history
- **operator_operates_mine:** Essroc Cement → ESSROC; 1982-11-18 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Italcementi Spa → Essroc Cement; 1982-11-18 to 2016-10-11; source msha-controller-operator-history
- **controller_controls_mine:** Heidelberg Materials AG → ESSROC; 2016-10-12 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Heidelberg Materials AG → Essroc Cement; 2016-10-12 to current/open; source msha-controller-operator-history