# Relationship history for MSHA mine 2301721

Current hierarchy: **Quality Stone Materials Company → Quality Stone Materials Company → Quality Stone & Materials Co-Quarry & Mi**

- 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

- **controller_controls_mine:** Quality Stone Materials Company → Quality Stone & Materials Co-Quarry & Mi; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Quality Stone Materials Company → Quality Stone & Materials Co-Quarry & Mi; 1978-03-09 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Quality Stone Materials Company → Quality Stone Materials Company; 1978-03-09 to current/open; source msha-controller-operator-history