# Relationship history for MSHA mine 4800602

Current hierarchy: **David  Brown → Wyo-Ben, Inc → Magnet Cove Mill**

- 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:** Magcobar Minerals Division → Magnet Cove Mill; 1950-01-01 to 1987-01-19; source msha-controller-operator-history
- **controller_controls_mine:** Dresser Industries Inc → Magnet Cove Mill; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Dresser Industries Inc → Magcobar Minerals Division; 1950-01-01 to 1987-01-19; source msha-controller-operator-history
- **controller_controls_mine:** David  Brown → Magnet Cove Mill; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Halliburton Co et al → Magnet Cove Mill; 1987-01-19 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** M-I Drilling Fluids Company → Magnet Cove Mill; 1987-01-20 to 1994-04-21; source msha-controller-operator-history
- **controller_controls_operator:** Halliburton Co et al → M-I Drilling Fluids Company; 1987-01-20 to 1994-04-21; source msha-controller-operator-history
- **controller_controls_operator:** Dresser Industries Inc et al → M-I Drilling Fluids Company; 1987-01-20 to 1994-04-21; source msha-controller-operator-history
- **controller_controls_mine:** Schlumberger Ltd → Magnet Cove Mill; 1994-02-28 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** M-I L L C → Magnet Cove Mill; 1994-04-22 to 2023-11-05; source msha-controller-operator-history
- **controller_controls_operator:** Schlumberger Ltd → M-I L L C; 1994-04-22 to 2023-11-05; source msha-controller-operator-history
- **operator_operates_mine:** Wyo-Ben, Inc → Magnet Cove Mill; 2023-11-06 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** David  Brown → Wyo-Ben, Inc; 2023-11-06 to current/open; source msha-controller-operator-history