# Relationship history for MSHA mine 1300148

Current hierarchy: **Amrize Ltd → Holcim (US) Inc → Mason City 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: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **operator_operates_mine:** Northwestern States Portland Cement Company → Mason City Plant & Quarry; 1950-01-01 to 1990-01-18; source msha-controller-operator-history
- **controller_controls_mine:** Jack  MacNider → Mason City Plant & Quarry; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Jack  MacNider → Northwestern States Portland Cement Company; 1950-01-01 to 1990-01-18; source msha-controller-operator-history
- **controller_controls_mine:** Holcim Ltd → Mason City Plant & Quarry; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Holnam Inc → Mason City Plant & Quarry; 1990-01-19 to 2001-12-31; source msha-controller-operator-history
- **controller_controls_operator:** Holcim Ltd → Holnam Inc; 1990-01-19 to 2001-12-31; source msha-controller-operator-history
- **controller_controls_mine:** Holcim Ltd → Mason City Plant & Quarry; 2001-12-12 to 2015-07-09; source msha-controller-operator-history
- **operator_operates_mine:** Holcim (US) Inc → Mason City Plant & Quarry; 2002-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Holcim Ltd → Holcim (US) Inc; 2002-01-01 to 2015-07-09; source msha-controller-operator-history
- **controller_controls_mine:** Holcim Ltd → Mason City Plant & Quarry; 2015-07-10 to 2025-06-22; source msha-controller-operator-history
- **controller_controls_operator:** Holcim Ltd → Holcim (US) Inc; 2015-07-10 to 2025-06-22; source msha-controller-operator-history
- **controller_controls_mine:** Amrize Ltd → Mason City Plant & Quarry; 2025-06-23 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Amrize Ltd → Holcim (US) Inc; 2025-06-23 to current/open; source msha-controller-operator-history