# Relationship history for MSHA mine 0900051

Current hierarchy: **Heidelberg Materials AG → Heidelberg Materials Southeast Agg., LLC → Toccoa 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:** North Georgia Crushed Stone Corp → Toccoa Quarry; 1950-01-01 to 1979-01-31; source msha-controller-operator-history
- **controller_controls_mine:** Ivy Corp → Toccoa Quarry; 1950-01-01 to 1979-01-31; source msha-controller-operator-history
- **controller_controls_operator:** Ivy Corp → North Georgia Crushed Stone Corp; 1950-01-01 to 1979-01-31; source msha-controller-operator-history
- **operator_operates_mine:** Davidson Mineral Properties Inc → Toccoa Quarry; 1979-02-01 to 1988-11-13; source msha-controller-operator-history
- **controller_controls_mine:** Koppers Company Inc → Toccoa Quarry; 1979-02-01 to 1988-11-13; source msha-controller-operator-history
- **controller_controls_operator:** Koppers Company Inc → Davidson Mineral Properties Inc; 1979-02-01 to 1988-11-13; source msha-controller-operator-history
- **controller_controls_mine:** Hanson PLC → Toccoa Quarry; 1988-11-14 to 2007-08-22; source msha-controller-operator-history
- **operator_operates_mine:** Hanson Aggregates East Inc → Toccoa Quarry; 1988-11-14 to 2002-01-31; source msha-controller-operator-history
- **controller_controls_mine:** Hanson PLC → Toccoa Quarry; 1988-11-14 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Hanson PLC → Hanson Aggregates East Inc; 1988-11-14 to 2002-01-31; source msha-controller-operator-history
- **operator_operates_mine:** Heidelberg Materials Southeast Agg., LLC → Toccoa Quarry; 2002-02-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Hanson PLC → Heidelberg Materials Southeast Agg., LLC; 2002-02-01 to 2007-08-22; source msha-controller-operator-history
- **controller_controls_mine:** Heidelberg Materials AG → Toccoa Quarry; 2007-08-23 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Heidelberg Materials AG → Heidelberg Materials Southeast Agg., LLC; 2007-08-23 to current/open; source msha-controller-operator-history