# Relationship history for MSHA mine 2600411

Current hierarchy: **Schlumberger Ltd → M-I Swaco- A Schlumberger Company → Greystone 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:** Magcobar Minerals Division → Greystone Mine; 1950-01-01 to 1992-09-30; source msha-controller-operator-history
- **controller_controls_mine:** Dresser Industries Inc → Greystone Mine; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Dresser Industries Inc → Magcobar Minerals Division; 1950-01-01 to 1992-09-30; source msha-controller-operator-history
- **controller_controls_mine:** Halliburton Co et al → Greystone Mine; 1987-01-19 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** M-I Drilling Fluids Company → Greystone Mine; 1992-10-01 to 1994-04-21; source msha-controller-operator-history
- **controller_controls_operator:** Halliburton Co et al → M-I Drilling Fluids Company; 1992-10-01 to 1994-04-21; source msha-controller-operator-history
- **controller_controls_operator:** Dresser Industries Inc et al → M-I Drilling Fluids Company; 1992-10-01 to 1994-04-21; source msha-controller-operator-history
- **controller_controls_mine:** Schlumberger Ltd → Greystone Mine; 1994-02-28 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** M-I Swaco- A Schlumberger Company → Greystone Mine; 1994-04-22 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Schlumberger Ltd → M-I Swaco- A Schlumberger Company; 1994-04-22 to current/open; source msha-controller-operator-history