# Relationship history for MSHA mine 3600620

Current hierarchy: **Rost Andrew J → Mt Savage Refractories Company Inc → Fort Hill**

- 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:** General Refractories Company → Fort Hill; 1950-01-01 to 1985-08-12; source msha-controller-operator-history
- **controller_controls_mine:** Dicalite Management Group LLC → Fort Hill; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Dicalite Management Group LLC → General Refractories Company; 1950-01-01 to 1985-08-12; source msha-controller-operator-history
- **operator_operates_mine:** Mt Savage Refractories Company Inc → Fort Hill; 1985-08-13 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Rost Andrew J Et Al → Fort Hill; 1985-08-13 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Rost Andrew J Et Al → Mt Savage Refractories Company Inc; 1985-08-13 to current/open; source msha-controller-operator-history