# Relationship history for MSHA mine 0503873

Current hierarchy: **Webbco Corp-Vulcan Resources → Great West Gold & Silver Inc → Vulcan**

- 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:** Great West Gold & Silver Inc → Vulcan; 1983-07-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Webbco Corp-Vulcan Resources Et Al → Vulcan; 1983-07-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Webbco Corp-Vulcan Resources Et Al → Great West Gold & Silver Inc; 1983-07-01 to current/open; source msha-controller-operator-history