# Relationship history for MSHA mine 0900107

Current hierarchy: **USG Corporation → A P Green Refractories Inc → Tharpe Mine**

- 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:** A P Green Refractories Inc → Tharpe Mine; 1950-01-01 to 1979-03-05; source msha-controller-operator-history
- **controller_controls_mine:** USG Corporation → Tharpe Mine; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** USG Corporation → A P Green Refractories Inc; 1950-01-01 to 1979-03-05; source msha-controller-operator-history
- **operator_operates_mine:** Calvin R Jones Contractor → Tharpe Mine; 1979-03-06 to 1981-01-08; source msha-controller-operator-history
- **controller_controls_mine:** Jones Calvin R → Tharpe Mine; 1979-03-06 to 1981-01-08; source msha-controller-operator-history
- **controller_controls_operator:** Jones Calvin R → Calvin R Jones Contractor; 1979-03-06 to 1981-01-08; source msha-controller-operator-history
- **operator_operates_mine:** A P Green Refractories Inc → Tharpe Mine; 1981-01-09 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** USG Corporation → A P Green Refractories Inc; 1981-01-09 to current/open; source msha-controller-operator-history