# Relationship history for MSHA mine 0900921

Current hierarchy: **Alcoa Inc → Dalton Alumina & Chemicals Company → Dalton Alumina & Chemicals 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: 2026-10-18T09:31:49.615908+00:00

## Valid-time edges

- **operator_operates_mine:** Dixie Chemicals Of Dalton Inc → Dalton Alumina & Chemicals Plant; 1980-02-01 to 1985-01-02; source msha-controller-operator-history
- **controller_controls_mine:** Manis Benjamin Reid → Dalton Alumina & Chemicals Plant; 1980-02-01 to 1985-01-02; source msha-controller-operator-history
- **controller_controls_operator:** Manis Benjamin Reid → Dixie Chemicals Of Dalton Inc; 1980-02-01 to 1985-01-02; source msha-controller-operator-history
- **operator_operates_mine:** Dalton Alumina & Chemicals Company → Dalton Alumina & Chemicals Plant; 1985-01-03 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Alcoa Inc → Dalton Alumina & Chemicals Plant; 1985-01-03 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Alcoa Inc → Dalton Alumina & Chemicals Company; 1985-01-03 to current/open; source msha-controller-operator-history