# Relationship history for MSHA mine 0600023

Current hierarchy: **BTR PLC → Tilcon Connecticut Inc → Farmington Quarry & 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:** New Haven Trap Rock-Tomasso Inc → Farmington Quarry & Mill; 1950-01-01 to 1979-04-22; source msha-controller-operator-history
- **controller_controls_mine:** Ashland Inc → Farmington Quarry & Mill; 1950-01-01 to 1979-04-22; source msha-controller-operator-history
- **controller_controls_operator:** Ashland Inc → New Haven Trap Rock-Tomasso Inc; 1950-01-01 to 1979-04-22; source msha-controller-operator-history
- **operator_operates_mine:** Tilcon Connecticut Inc → Farmington Quarry & Mill; 1979-04-23 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** BTR PLC → Farmington Quarry & Mill; 1979-04-23 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** BTR PLC → Tilcon Connecticut Inc; 1979-04-23 to current/open; source msha-controller-operator-history