# Relationship history for MSHA mine 1505333

Current hierarchy: **Haywood Billy H → Tangent Mining Company Inc → Tangent Mining Co Inc**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **operator_operates_mine:** National Mines Corp → Tangent Mining Co Inc; 1950-01-01 to 1989-09-26; source msha-controller-operator-history
- **controller_controls_mine:** Nippon Kokan K K et al → Tangent Mining Co Inc; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Nippon Kokan K K et al → National Mines Corp; 1950-01-01 to 1989-09-26; source msha-controller-operator-history
- **operator_operates_mine:** Tangent Mining Company Inc → Tangent Mining Co Inc; 1989-09-27 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Haywood Billy H → Tangent Mining Co Inc; 1989-09-27 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Haywood Billy H → Tangent Mining Company Inc; 1989-09-27 to current/open; source msha-controller-operator-history