# Relationship history for MSHA mine 0402509

Current hierarchy: **Richard B  Harmon → Standard Industrial Minerals Inc → Tecopa Plant & Mill (Beck)**

- 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:** Standard Slag Company → Tecopa Plant & Mill (Beck); 1950-01-01 to 1987-08-31; source msha-controller-operator-history
- **controller_controls_mine:** Standard Slag Company → Tecopa Plant & Mill (Beck); 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Standard Slag Company → Standard Slag Company; 1950-01-01 to 1987-08-31; source msha-controller-operator-history
- **operator_operates_mine:** Standard Industrial Minerals Inc → Tecopa Plant & Mill (Beck); 1987-09-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Richard B  Harmon et al → Tecopa Plant & Mill (Beck); 1987-09-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Richard B  Harmon et al → Standard Industrial Minerals Inc; 1987-09-01 to current/open; source msha-controller-operator-history