# Relationship history for MSHA mine 2902047

Current hierarchy: **Kelly  Armstrong → Copar Pumice Company, Inc. → SAN YSIDRO MILL**

- 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:** Richard P  Cook → SAN YSIDRO MILL; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Copar Pumice Company → SAN YSIDRO MILL; 1990-05-01 to 1998-05-12; source msha-controller-operator-history
- **controller_controls_operator:** Richard P  Cook → Copar Pumice Company; 1990-05-01 to 1998-05-12; source msha-controller-operator-history
- **operator_operates_mine:** Copar Pumice Company, Inc. → SAN YSIDRO MILL; 1998-05-13 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Kelly  Armstrong → SAN YSIDRO MILL; 1998-05-13 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Kelly  Armstrong → Copar Pumice Company, Inc.; 1998-05-13 to current/open; source msha-controller-operator-history