# Relationship history for MSHA mine 1102837

Current hierarchy: **Covia Holdings LLC → Unimin Specialty Minerals Inc → BIRK 1 Pit**

- 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:** Asea Brown Boveri Ltd (ABB) → BIRK 1 Pit; 1983-03-23 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Illinois Minerals Company → BIRK 1 Pit; 1985-09-01 to 1989-10-10; source msha-controller-operator-history
- **controller_controls_operator:** Asea Brown Boveri Ltd (ABB) → Illinois Minerals Company; 1985-09-01 to 1989-10-10; source msha-controller-operator-history
- **controller_controls_mine:** S C R-Sibelco Nv et al → BIRK 1 Pit; 1986-06-30 to 2020-12-31; source msha-controller-operator-history
- **operator_operates_mine:** Unimin Specialty Minerals Inc → BIRK 1 Pit; 1989-10-11 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** S C R-Sibelco Nv et al → Unimin Specialty Minerals Inc; 1989-10-11 to 2020-12-31; source msha-controller-operator-history
- **controller_controls_mine:** Covia Holdings LLC → BIRK 1 Pit; 2021-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Covia Holdings LLC → Unimin Specialty Minerals Inc; 2021-01-01 to current/open; source msha-controller-operator-history