# Relationship history for MSHA mine 3605671

Current hierarchy: **Zigarski Albert → B & Z Coal Company → No 1 Slope**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-13T11:19:05.459773+00:00

## Valid-time edges

- **operator_operates_mine:** B & Z Coal Company → No 1 Slope; 1975-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Zigarski Albert Et Al → No 1 Slope; 1975-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Zigarski Albert Et Al → B & Z Coal Company; 1975-01-01 to current/open; source msha-controller-operator-history