# Relationship history for MSHA mine 0900749

Current hierarchy: **Jones Robert E → Zyrian Stone Inc → Mineral Bluff Quarry & Plant**

- 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:** Zyrian Stone Inc → Mineral Bluff Quarry & Plant; 1950-01-01 to 1986-12-31; source msha-controller-operator-history
- **controller_controls_mine:** Hensen Carmel → Mineral Bluff Quarry & Plant; 1950-01-01 to 1986-12-31; source msha-controller-operator-history
- **controller_controls_operator:** Hensen Carmel → Zyrian Stone Inc; 1950-01-01 to 1986-12-31; source msha-controller-operator-history
- **operator_operates_mine:** Zyrian Stone Inc → Mineral Bluff Quarry & Plant; 1987-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Jones Robert E → Mineral Bluff Quarry & Plant; 1987-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Jones Robert E → Zyrian Stone Inc; 1987-01-01 to current/open; source msha-controller-operator-history