# Relationship history for MSHA mine 0504357

Current hierarchy: **Norton Floyd E → Toltec & Granger Mining Corp → Toltec & Granger 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:** Norton Floyd E → Toltec & Granger Mill; 1987-07-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Toltec & Granger Mining Corp → Toltec & Granger Mill; 1988-06-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Norton Floyd E → Toltec & Granger Mining Corp; 1988-06-01 to current/open; source msha-controller-operator-history