# Relationship history for MSHA mine 3600009

Current hierarchy: **Magnesita Refratarios SA → Magnesita Refractories Company → York Plant**

- 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:** J E Baker Company → York Plant; 1950-01-01 to 2001-05-17; source msha-controller-operator-history
- **controller_controls_mine:** David  Manchester → York Plant; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** David  Manchester → J E Baker Company; 1950-01-01 to 2001-05-17; source msha-controller-operator-history
- **operator_operates_mine:** Magnesita Refractories Company → York Plant; 2001-05-18 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Lhoist Group → York Plant; 2001-05-18 to 2009-12-09; source msha-controller-operator-history
- **controller_controls_operator:** Lhoist Group → Magnesita Refractories Company; 2001-05-18 to 2009-12-09; source msha-controller-operator-history
- **controller_controls_mine:** Magnesita Refratarios SA → York Plant; 2009-12-10 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Magnesita Refratarios SA → Magnesita Refractories Company; 2009-12-10 to current/open; source msha-controller-operator-history