# Relationship history for MSHA mine 0900010

Current hierarchy: **Harmony Blue Granite Company → Middle Georgia Quarrying Company → Dixie Blue 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:** Dixie Granite Company → Dixie Blue Quarry; 1950-01-01 to 1978-03-31; source msha-controller-operator-history
- **controller_controls_mine:** Dixie Granite Company → Dixie Blue Quarry; 1950-01-01 to 1978-03-31; source msha-controller-operator-history
- **controller_controls_operator:** Dixie Granite Company → Dixie Granite Company; 1950-01-01 to 1978-03-31; source msha-controller-operator-history
- **operator_operates_mine:** Middle Georgia Quarrying Company → Dixie Blue Quarry; 1978-04-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Harmony Blue Granite Company → Dixie Blue Quarry; 1978-04-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Harmony Blue Granite Company → Middle Georgia Quarrying Company; 1978-04-01 to current/open; source msha-controller-operator-history