# Relationship history for MSHA mine 3610091

Current hierarchy: **Edward  Helfrich → Mallard Contracting → Glen Burn - Harmony Mine**

- 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:** Edward  Helfrich et al → Glen Burn - Harmony Mine; 1971-08-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Mallard Contracting → Glen Burn - Harmony Mine; 2013-11-08 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Edward  Helfrich et al → Mallard Contracting; 2013-11-08 to current/open; source msha-controller-operator-history