# Relationship history for MSHA mine 4801714

Current hierarchy: **National Oilwell Varco Inc → National Oilwell Varco LP → Evanston Barite 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: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **controller_controls_mine:** Spirit Minerals Management LLC et al → Evanston Barite Mill; 2006-08-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Spirit Minerals, LP → Evanston Barite Mill; 2007-10-01 to 2009-07-12; source msha-controller-operator-history
- **controller_controls_operator:** Spirit Minerals Management LLC et al → Spirit Minerals, LP; 2007-10-01 to 2009-07-12; source msha-controller-operator-history
- **operator_operates_mine:** National Oilwell Varco LP → Evanston Barite Mill; 2009-07-13 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** National Oilwell Varco Inc → Evanston Barite Mill; 2009-07-13 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** National Oilwell Varco Inc → National Oilwell Varco LP; 2009-07-13 to current/open; source msha-controller-operator-history