# Relationship history for MSHA mine 3500978

Current hierarchy: **A J  Urbanek → Circle Construction Company → 102-TONQUIN QUARRY**

- 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:** Circle Construction Company → 102-TONQUIN QUARRY; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** A J  Urbanek → 102-TONQUIN QUARRY; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** A J  Urbanek → Circle Construction Company; 1950-01-01 to current/open; source msha-controller-operator-history