# Relationship history for MSHA mine 2101150

Current hierarchy: **Bruce D  Haslerud → Black Diamond Granules Inc → Twin City Silica Pit & Mill**

- 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

- **operator_operates_mine:** Abrasive Technologies Inc → Twin City Silica Pit & Mill; 1950-01-01 to 2007-03-21; source msha-controller-operator-history
- **controller_controls_mine:** Bruce D  Haslerud  et al → Twin City Silica Pit & Mill; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Bruce D  Haslerud  et al → Abrasive Technologies Inc; 1950-01-01 to 2007-03-21; source msha-controller-operator-history
- **operator_operates_mine:** Black Diamond Granules Inc → Twin City Silica Pit & Mill; 2007-03-22 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Bruce D  Haslerud  et al → Twin City Silica Pit & Mill; 2007-03-22 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Bruce D  Haslerud  et al → Black Diamond Granules Inc; 2007-03-22 to current/open; source msha-controller-operator-history