# Relationship history for MSHA mine 1515947

Current hierarchy: **Melinda K  Brock → Sand Source LLC → SAND SOURCE, LLC**

- 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:** M E R C → SAND SOURCE, LLC; 1987-03-01 to 1993-03-03; source msha-controller-operator-history
- **controller_controls_mine:** Schmitt Harold → SAND SOURCE, LLC; 1987-03-01 to 1993-03-03; source msha-controller-operator-history
- **controller_controls_operator:** Schmitt Harold → M E R C; 1987-03-01 to 1993-03-03; source msha-controller-operator-history
- **operator_operates_mine:** Overton Products → SAND SOURCE, LLC; 1993-03-04 to 1993-06-28; source msha-controller-operator-history
- **controller_controls_mine:** Overton Tommy → SAND SOURCE, LLC; 1993-03-04 to 1993-06-28; source msha-controller-operator-history
- **controller_controls_operator:** Overton Tommy → Overton Products; 1993-03-04 to 1993-06-28; source msha-controller-operator-history
- **operator_operates_mine:** Sand Source Inc → SAND SOURCE, LLC; 1993-06-29 to 2006-05-31; source msha-controller-operator-history
- **controller_controls_mine:** Burnside Melvin → SAND SOURCE, LLC; 1993-06-29 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Burnside Melvin → Sand Source Inc; 1993-06-29 to 2006-05-31; source msha-controller-operator-history
- **operator_operates_mine:** Sand Source LLC → SAND SOURCE, LLC; 2006-06-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Melinda K  Brock et al → SAND SOURCE, LLC; 2006-06-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Melinda K  Brock et al → Sand Source LLC; 2006-06-01 to current/open; source msha-controller-operator-history