# Relationship history for MSHA mine 3304251

Current hierarchy: **Fairmount Santrol → Best Sand Corp → BEST SAND CORPORATION**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **controller_controls_mine:** Melvin  Schrader → BEST SAND CORPORATION; 1981-10-01 to 1994-09-30; source msha-controller-operator-history
- **operator_operates_mine:** Schrader Sand & Gravel → BEST SAND CORPORATION; 1991-12-01 to 1994-09-30; source msha-controller-operator-history
- **controller_controls_operator:** Melvin  Schrader → Schrader Sand & Gravel; 1991-12-01 to 1994-09-30; source msha-controller-operator-history
- **operator_operates_mine:** Best Sand Corp → BEST SAND CORPORATION; 1994-10-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Fairmount Santrol → BEST SAND CORPORATION; 1994-10-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Fairmount Santrol → Best Sand Corp; 1994-10-01 to current/open; source msha-controller-operator-history