# Relationship history for MSHA mine 4400026

Current hierarchy: **Carmeuse Holding SA → O-N Minerals (Chemstone Company) → Strasburg 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:** Chemstone Corp → Strasburg Quarry; 1950-01-01 to 1984-07-31; source msha-controller-operator-history
- **controller_controls_mine:** Engelhard Corp → Strasburg Quarry; 1950-01-01 to 1984-07-31; source msha-controller-operator-history
- **controller_controls_operator:** Engelhard Corp → Chemstone Corp; 1950-01-01 to 1984-07-31; source msha-controller-operator-history
- **operator_operates_mine:** Chemstone Corp → Strasburg Quarry; 1984-08-01 to 1994-07-20; source msha-controller-operator-history
- **controller_controls_mine:** George  O'Neill  et al → Strasburg Quarry; 1984-08-01 to 1994-07-20; source msha-controller-operator-history
- **controller_controls_operator:** George  O'Neill  et al → Chemstone Corp; 1984-08-01 to 1994-07-20; source msha-controller-operator-history
- **operator_operates_mine:** Chemstone Corp → Strasburg Quarry; 1994-07-21 to 1998-06-21; source msha-controller-operator-history
- **controller_controls_mine:** Global Stone Corp → Strasburg Quarry; 1994-07-21 to 1998-06-21; source msha-controller-operator-history
- **controller_controls_operator:** Global Stone Corp → Chemstone Corp; 1994-07-21 to 1998-06-21; source msha-controller-operator-history
- **operator_operates_mine:** O-N Minerals (Chemstone Company) → Strasburg Quarry; 1998-06-22 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Oglebay Norton Company → Strasburg Quarry; 1998-06-22 to 2008-02-12; source msha-controller-operator-history
- **controller_controls_operator:** Oglebay Norton Company → O-N Minerals (Chemstone Company); 1998-06-22 to 2008-02-12; source msha-controller-operator-history
- **controller_controls_mine:** Carmeuse Holding SA → Strasburg Quarry; 2008-02-13 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Carmeuse Holding SA → O-N Minerals (Chemstone Company); 2008-02-13 to current/open; source msha-controller-operator-history