# Relationship history for MSHA mine 1509520

Current hierarchy: **Frost J A Jr → Kentucky Jaf Coals Inc → Alcona Mine**

- 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:** Kentucky Jaf Coals Inc → Alcona Mine; 1976-02-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Frost J A Jr → Alcona Mine; 1976-02-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Frost J A Jr → Kentucky Jaf Coals Inc; 1976-02-01 to current/open; source msha-controller-operator-history