# Relationship history for MSHA mine 3800054

Current hierarchy: **Standard Industries Holdings Inc → W R Grace & Company-Conn → National Kaolin Products**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-18T09:31:49.615908+00:00

## Valid-time edges

- **controller_controls_mine:** W R Grace & Company → National Kaolin Products; 1950-01-01 to 2021-09-21; source msha-controller-operator-history
- **operator_operates_mine:** National Kaolin Products Company → National Kaolin Products; 1950-01-01 to 1980-08-11; source msha-controller-operator-history
- **controller_controls_mine:** S G  Leoffler → National Kaolin Products; 1950-01-01 to 1980-08-11; source msha-controller-operator-history
- **controller_controls_operator:** S G  Leoffler → National Kaolin Products Company; 1950-01-01 to 1980-08-11; source msha-controller-operator-history
- **operator_operates_mine:** W R Grace & Company-Conn → National Kaolin Products; 1980-08-12 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** W R Grace & Company → W R Grace & Company-Conn; 1980-08-12 to 2021-09-21; source msha-controller-operator-history
- **controller_controls_mine:** Standard Industries Holdings Inc → National Kaolin Products; 2021-09-22 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Standard Industries Holdings Inc → W R Grace & Company-Conn; 2021-09-22 to current/open; source msha-controller-operator-history