# Relationship history for MSHA mine 2602111

Current hierarchy: **Cyrus W  Spurlino → Silver State Materials Corp → Laughlin Midby Site**

- 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:** Harold  Ruf et al → Laughlin Midby Site; 1987-03-12 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Westroc Inc → Laughlin Midby Site; 1989-06-01 to 1990-02-25; source msha-controller-operator-history
- **controller_controls_operator:** Harold  Ruf et al → Westroc Inc; 1989-06-01 to 1990-02-25; source msha-controller-operator-history
- **controller_controls_operator:** Mike  Ellis et al → Westroc Inc; 1989-06-01 to 1990-02-25; source msha-controller-operator-history
- **operator_operates_mine:** Silver State Materials Corp → Laughlin Midby Site; 1990-02-26 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Cyrus W  Spurlino → Laughlin Midby Site; 1990-02-26 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Cyrus W  Spurlino → Silver State Materials Corp; 1990-02-26 to current/open; source msha-controller-operator-history