# Relationship history for MSHA mine 1509997

Current hierarchy: **Montrie E F → Montrie Mining Corp → Brown Mountain Surface**

- 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:** Montrie E F → Brown Mountain Surface; 1974-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Montrie Mining Corp → Brown Mountain Surface; 1976-09-30 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Montrie E F → Montrie Mining Corp; 1976-09-30 to current/open; source msha-controller-operator-history