# Relationship history for MSHA mine 0200022

Current hierarchy: **Lhoist Group → Martin Marietta Materials, Inc. → DOUGLAS 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: 2026-10-13T11:19:05.459773+00:00

## Valid-time edges

- **operator_operates_mine:** Can-Am Corp → DOUGLAS PLANT; 1950-01-01 to 1986-12-22; source msha-controller-operator-history
- **controller_controls_mine:** B-X International Inc → DOUGLAS PLANT; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** B-X International Inc → Can-Am Corp; 1950-01-01 to 1986-12-22; source msha-controller-operator-history
- **controller_controls_mine:** Chemical Lime Company → DOUGLAS PLANT; 1986-12-04 to 1998-12-30; source msha-controller-operator-history
- **operator_operates_mine:** Lhoist North America of Arizona Inc. → DOUGLAS PLANT; 1986-12-23 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Chemical Lime Company → Lhoist North America of Arizona Inc.; 1986-12-23 to 1998-12-30; source msha-controller-operator-history
- **controller_controls_mine:** Lhoist Group → DOUGLAS PLANT; 1998-12-31 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Lhoist Group → Lhoist North America of Arizona Inc.; 1998-12-31 to current/open; source msha-controller-operator-history