# Relationship history for MSHA mine 4300182

Current hierarchy: **Omya Industries Inc → Vermarco Ground Products → Dolomite Quarry And 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:** Vermarco Ground Products → Dolomite Quarry And Mill; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Omya Industries Inc → Dolomite Quarry And Mill; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Omya Industries Inc → Vermarco Ground Products; 1950-01-01 to current/open; source msha-controller-operator-history