# Relationship history for MSHA mine 3300351

Current hierarchy: **Minerals Research & Recovery Inc → Minerals Research & Recovery Of Ohio Inc → Comer Quarry & 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: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **operator_operates_mine:** Gunning Refractories Inc → Comer Quarry & Mill; 1950-01-01 to 1981-03-22; source msha-controller-operator-history
- **controller_controls_mine:** B M I Inc → Comer Quarry & Mill; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** B M I Inc → Gunning Refractories Inc; 1950-01-01 to 1981-03-22; source msha-controller-operator-history
- **operator_operates_mine:** Minerals Research & Recovery Of Ohio Inc → Comer Quarry & Mill; 1981-03-23 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Minerals Research & Recovery Inc → Comer Quarry & Mill; 1981-03-23 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Minerals Research & Recovery Inc → Minerals Research & Recovery Of Ohio Inc; 1981-03-23 to current/open; source msha-controller-operator-history