# Relationship history for MSHA mine 0901232

Current hierarchy: **USS Holdings Inc → US Silica Company → Millen Plant**

- 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:** Gary A  Kolstad et al → Millen Plant; 1987-06-30 to 2020-06-30; source msha-controller-operator-history
- **controller_controls_mine:** USS Holdings Inc → Millen Plant; 1996-03-09 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** CARBO Ceramics → Millen Plant; 2014-09-12 to 2019-05-13; source msha-controller-operator-history
- **controller_controls_operator:** Gary A  Kolstad et al → CARBO Ceramics; 2014-09-12 to 2019-05-13; source msha-controller-operator-history
- **operator_operates_mine:** US Silica Company → Millen Plant; 2019-05-14 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** USS Holdings Inc → US Silica Company; 2019-05-14 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Wilks Brothers LLC → Millen Plant; 2020-07-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Wilks Brothers LLC → CARBO Ceramics; 2020-07-01 to 2019-05-13; source msha-controller-operator-history