# Relationship history for MSHA mine 0504417

Current hierarchy: **Hecla Mining Company → Mwca Inc → SAN ACACIO PLANT**

- 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

- **controller_controls_mine:** Hecla Mining Company → SAN ACACIO PLANT; 1987-06-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Mwca Inc → SAN ACACIO PLANT; 1990-02-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Hecla Mining Company → Mwca Inc; 1990-02-01 to current/open; source msha-controller-operator-history