# Relationship history for MSHA mine 0400534

Current hierarchy: **Minerals Technologies Inc → Pfizer Inc → P V Clay 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

- **controller_controls_mine:** Minerals Technologies Inc → P V Clay Mine; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Desert Mineral Products Corp → P V Clay Mine; 1950-01-01 to 1982-07-31; source msha-controller-operator-history
- **controller_controls_mine:** Continental Minerals Corp → P V Clay Mine; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Continental Minerals Corp → Desert Mineral Products Corp; 1950-01-01 to 1982-07-31; source msha-controller-operator-history
- **operator_operates_mine:** Pfizer Inc → P V Clay Mine; 1982-08-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Minerals Technologies Inc → Pfizer Inc; 1982-08-01 to current/open; source msha-controller-operator-history