# Relationship history for MSHA mine 4200906

Current hierarchy: **Materion Corporation → Brush Wellman Inc → Brush Wellman Delta 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:** Brush Wellman Inc → Brush Wellman Delta Mill; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Materion Corporation → Brush Wellman Delta Mill; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Materion Corporation → Brush Wellman Inc; 1950-01-01 to current/open; source msha-controller-operator-history