# Relationship history for MSHA mine 1800214

Current hierarchy: **Harford Talc Company → Harford Talc Company → Harford Talc Company 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: 2026-10-18T09:31:49.615908+00:00

## Valid-time edges

- **operator_operates_mine:** Harford Talc Company → Harford Talc Company Quarry And Mill; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Harford Talc Company → Harford Talc Company Quarry And Mill; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Harford Talc Company → Harford Talc Company; 1950-01-01 to current/open; source msha-controller-operator-history