# Relationship history for MSHA mine 2601551

Current hierarchy: **Amrize Ltd → Frehner Construction Company Inc → Portable Crusher Ft6**

- 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:** Lander Barite Inc → Portable Crusher Ft6; 1979-01-01 to 1991-08-29; source msha-controller-operator-history
- **controller_controls_mine:** Johnson James → Portable Crusher Ft6; 1979-01-01 to 1991-08-29; source msha-controller-operator-history
- **controller_controls_operator:** Johnson James → Lander Barite Inc; 1979-01-01 to 1991-08-29; source msha-controller-operator-history
- **controller_controls_mine:** Garth  Frehner → Portable Crusher Ft6; 1983-08-01 to 2004-05-09; source msha-controller-operator-history
- **operator_operates_mine:** Frehner Construction Company Inc → Portable Crusher Ft6; 1991-08-30 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Garth  Frehner → Frehner Construction Company Inc; 1991-08-30 to 2004-05-09; source msha-controller-operator-history
- **controller_controls_mine:** Aggregate Industries PLC → Portable Crusher Ft6; 2004-05-10 to 2009-04-29; source msha-controller-operator-history
- **controller_controls_operator:** Aggregate Industries PLC → Frehner Construction Company Inc; 2004-05-10 to 2009-04-29; source msha-controller-operator-history
- **controller_controls_mine:** Holcim Ltd → Portable Crusher Ft6; 2009-04-30 to 2015-07-09; source msha-controller-operator-history
- **controller_controls_operator:** Holcim Ltd → Frehner Construction Company Inc; 2009-04-30 to 2015-07-09; source msha-controller-operator-history
- **controller_controls_mine:** Holcim Ltd → Portable Crusher Ft6; 2015-07-10 to 2025-06-22; source msha-controller-operator-history
- **controller_controls_operator:** Holcim Ltd → Frehner Construction Company Inc; 2015-07-10 to 2025-06-22; source msha-controller-operator-history
- **controller_controls_mine:** Amrize Ltd → Portable Crusher Ft6; 2025-06-23 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Amrize Ltd → Frehner Construction Company Inc; 2025-06-23 to current/open; source msha-controller-operator-history