# Relationship history for MSHA mine 2902167

Current hierarchy: **David A  Sanchez → San Bar Materials LLC → San Bar Materials**

- 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:** Southwest Laser Inc → San Bar Materials; 1997-06-01 to 2007-01-02; source msha-controller-operator-history
- **controller_controls_mine:** Erich F  Barmann → San Bar Materials; 1997-06-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Erich F  Barmann → Southwest Laser Inc; 1997-06-01 to 2007-01-02; source msha-controller-operator-history
- **operator_operates_mine:** San Bar Materials LLC → San Bar Materials; 2007-01-03 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** David A  Sanchez → San Bar Materials; 2007-01-03 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** David A  Sanchez → San Bar Materials LLC; 2007-01-03 to current/open; source msha-controller-operator-history