# Relationship history for MSHA mine 4201392

Current hierarchy: **Rio Tinto Group → Kennecott Utah Copper LLC → Kennecott Keystone Underground**

- 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:** Kennecott Minerals Company → Kennecott Keystone Underground; 1950-01-01 to 1981-06-03; source msha-controller-operator-history
- **controller_controls_mine:** Kennecott Copper Corp → Kennecott Keystone Underground; 1950-01-01 to 1981-06-03; source msha-controller-operator-history
- **controller_controls_operator:** Kennecott Copper Corp → Kennecott Minerals Company; 1950-01-01 to 1981-06-03; source msha-controller-operator-history
- **operator_operates_mine:** Kennecott/New Mines Development Division → Kennecott Keystone Underground; 1981-06-04 to 2006-05-07; source msha-controller-operator-history
- **controller_controls_mine:** British Petroleum Company PLC → Kennecott Keystone Underground; 1981-06-04 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** British Petroleum Company PLC → Kennecott/New Mines Development Division; 1981-06-04 to 2006-05-07; source msha-controller-operator-history
- **controller_controls_mine:** Rio Tinto Group → Kennecott Keystone Underground; 1989-06-30 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Kennecott Utah Copper LLC → Kennecott Keystone Underground; 2006-05-08 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Rio Tinto Group → Kennecott Utah Copper LLC; 2006-05-08 to current/open; source msha-controller-operator-history