# Relationship history for MSHA mine 4002860

Current hierarchy: **De Voe Robert F → Black Mountain Mining Corp → No 1 Strip**

- 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:** Black Mountain Mining Corp → No 1 Strip; 1984-09-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** De Voe Robert F Et Al → No 1 Strip; 1984-09-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** De Voe Robert F Et Al → Black Mountain Mining Corp; 1984-09-01 to current/open; source msha-controller-operator-history