# Relationship history for MSHA mine 0400023

Current hierarchy: **Vulcan Materials Company → CalMat Co → Napa 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:** Basalt Rock Div-Dillingham Heavy Const Inc → Napa Quarry; 1950-01-01 to 1986-05-06; source msha-controller-operator-history
- **controller_controls_mine:** Dillingham Construction Corp → Napa Quarry; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Dillingham Construction Corp → Basalt Rock Div-Dillingham Heavy Const Inc; 1950-01-01 to 1986-05-06; source msha-controller-operator-history
- **controller_controls_mine:** James M  Syar et al → Napa Quarry; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Syar Industries Inc → Napa Quarry; 1986-05-07 to 2022-08-12; source msha-controller-operator-history
- **controller_controls_operator:** James M  Syar et al → Syar Industries Inc; 1986-05-07 to 2022-08-12; source msha-controller-operator-history
- **controller_controls_mine:** Legacy Vulcan Corp (Form:Vulcan Materials Co) → Napa Quarry; 1999-01-06 to 2007-11-15; source msha-controller-operator-history
- **controller_controls_mine:** Vulcan Materials Company → Napa Quarry; 2007-11-16 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** CalMat Co → Napa Quarry; 2022-08-13 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Vulcan Materials Company → CalMat Co; 2022-08-13 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Legacy Vulcan Corp (Form:Vulcan Materials Co) → CalMat Co; 2022-08-13 to 2007-11-15; source msha-controller-operator-history