# Relationship history for MSHA mine 0300028

Current hierarchy: **Holcim Ltd → Holcim (US), Inc → Okay Plant & 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: 2026-10-13T11:19:05.459773+00:00

## Valid-time edges

- **operator_operates_mine:** Ideal Basic Industries-Cement Division → Okay Plant & Quarry; 1950-01-01 to 1989-06-08; source msha-controller-operator-history
- **controller_controls_mine:** Ideal Basic Industries Inc → Okay Plant & Quarry; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Ideal Basic Industries Inc → Ideal Basic Industries-Cement Division; 1950-01-01 to 1989-06-08; source msha-controller-operator-history
- **controller_controls_mine:** Holcim Ltd → Okay Plant & Quarry; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Holnam Inc → Okay Plant & Quarry; 1989-06-09 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Holcim Ltd → Holnam Inc; 1989-06-09 to current/open; source msha-controller-operator-history