# Relationship history for MSHA mine 3600006

Current hierarchy: **Buzzi S p A → Buzzi Unicem USA → Hercules Cement LP**

- 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:** Hercules Cement Company → Hercules Cement LP; 1950-01-01 to 1979-12-06; source msha-controller-operator-history
- **controller_controls_mine:** Amcord Inc → Hercules Cement LP; 1950-01-01 to 1979-12-06; source msha-controller-operator-history
- **controller_controls_operator:** Amcord Inc → Hercules Cement Company; 1950-01-01 to 1979-12-06; source msha-controller-operator-history
- **operator_operates_mine:** Hercules Cement Company → Hercules Cement LP; 1979-12-07 to 1980-12-13; source msha-controller-operator-history
- **controller_controls_mine:** Hanson PLC → Hercules Cement LP; 1979-12-07 to 1980-12-13; source msha-controller-operator-history
- **controller_controls_operator:** Hanson PLC → Hercules Cement Company; 1979-12-07 to 1980-12-13; source msha-controller-operator-history
- **operator_operates_mine:** Buzzi Unicem USA → Hercules Cement LP; 1980-12-14 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Buzzi S p A → Hercules Cement LP; 1980-12-14 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Buzzi S p A → Buzzi Unicem USA; 1980-12-14 to current/open; source msha-controller-operator-history