# Relationship history for MSHA mine 2000375

Current hierarchy: **NG Operations LLC → Gold Bond Building Products, LLC → TAWAS QUARRY**

- 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:** Gold Bond Building Products → TAWAS QUARRY; 1950-01-01 to 1993-06-30; source msha-controller-operator-history
- **controller_controls_mine:** Lafarge S A → TAWAS QUARRY; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Lafarge S A → Gold Bond Building Products; 1950-01-01 to 1993-06-30; source msha-controller-operator-history
- **operator_operates_mine:** National Gypsum Company → TAWAS QUARRY; 1993-07-01 to 1995-09-20; source msha-controller-operator-history
- **controller_controls_mine:** National Gypsum Company → TAWAS QUARRY; 1993-07-01 to 1995-09-20; source msha-controller-operator-history
- **controller_controls_operator:** National Gypsum Company → National Gypsum Company; 1993-07-01 to 1995-09-20; source msha-controller-operator-history
- **operator_operates_mine:** New NGC Incorporated → TAWAS QUARRY; 1995-09-21 to 2021-02-01; source msha-controller-operator-history
- **controller_controls_mine:** Spangler Companies Inc → TAWAS QUARRY; 1995-09-21 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Spangler Companies Inc → New NGC Incorporated; 1995-09-21 to 2021-02-01; source msha-controller-operator-history
- **controller_controls_mine:** NG Operations LLC → TAWAS QUARRY; 2021-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Gold Bond Building Products, LLC → TAWAS QUARRY; 2021-02-02 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** NG Operations LLC → Gold Bond Building Products, LLC; 2021-02-02 to current/open; source msha-controller-operator-history