# Relationship history for MSHA mine 2200630

Current hierarchy: **Covia Holdings LLC → Unimin Corp → Sledge 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:** S C R-Sibelco Nv et al → Sledge Mine; 1950-01-01 to 2020-12-31; source msha-controller-operator-history
- **controller_controls_mine:** Watts Blake Bearne & Company Plc → Sledge Mine; 1989-04-01 to 1999-09-30; source msha-controller-operator-history
- **operator_operates_mine:** United Clays Inc → Sledge Mine; 1991-03-01 to 1999-09-30; source msha-controller-operator-history
- **controller_controls_operator:** Watts Blake Bearne & Company Plc → United Clays Inc; 1991-03-01 to 1999-09-30; source msha-controller-operator-history
- **operator_operates_mine:** Unimin Corp → Sledge Mine; 1999-10-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** S C R-Sibelco Nv et al → Unimin Corp; 1999-10-01 to 2020-12-31; source msha-controller-operator-history
- **controller_controls_mine:** Covia Holdings LLC → Sledge Mine; 2021-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Covia Holdings LLC → Unimin Corp; 2021-01-01 to current/open; source msha-controller-operator-history