# Relationship history for MSHA mine 2602628

Current hierarchy: **Amrize Ltd → Bardon Materials → Crystal Ridge**

- 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

- **controller_controls_mine:** Garth  Frehner → Crystal Ridge; 1983-08-01 to 2004-05-09; source msha-controller-operator-history
- **controller_controls_mine:** Aggregate Industries PLC → Crystal Ridge; 2004-05-10 to 2009-04-29; source msha-controller-operator-history
- **operator_operates_mine:** Bardon Materials → Crystal Ridge; 2007-12-04 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Garth  Frehner → Bardon Materials; 2007-12-04 to 2004-05-09; source msha-controller-operator-history
- **controller_controls_operator:** Aggregate Industries PLC → Bardon Materials; 2007-12-04 to 2009-04-29; source msha-controller-operator-history
- **controller_controls_mine:** Holcim Ltd → Crystal Ridge; 2009-04-30 to 2015-07-09; source msha-controller-operator-history
- **controller_controls_operator:** Holcim Ltd → Bardon Materials; 2009-04-30 to 2015-07-09; source msha-controller-operator-history
- **controller_controls_mine:** Holcim Ltd → Crystal Ridge; 2015-07-10 to 2025-06-22; source msha-controller-operator-history
- **controller_controls_operator:** Holcim Ltd → Bardon Materials; 2015-07-10 to 2025-06-22; source msha-controller-operator-history
- **controller_controls_mine:** Amrize Ltd → Crystal Ridge; 2025-06-23 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Amrize Ltd → Bardon Materials; 2025-06-23 to current/open; source msha-controller-operator-history