# Relationship history for MSHA mine 0503804

Current hierarchy: **Chemetech Corp → Chemetech Corp → Precious Metals Refining 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

- **operator_operates_mine:** Strategic Metals International Inc → Precious Metals Refining Plant; 1982-08-01 to 1985-05-21; source msha-controller-operator-history
- **controller_controls_mine:** Thomas P  Clark → Precious Metals Refining Plant; 1982-08-01 to 1985-05-21; source msha-controller-operator-history
- **controller_controls_operator:** Thomas P  Clark → Strategic Metals International Inc; 1982-08-01 to 1985-05-21; source msha-controller-operator-history
- **controller_controls_mine:** Chemetech Corp → Precious Metals Refining Plant; 1983-11-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Chemetech Corp → Precious Metals Refining Plant; 1985-05-22 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Chemetech Corp → Chemetech Corp; 1985-05-22 to current/open; source msha-controller-operator-history