# Relationship history for MSHA mine 0900889

Current hierarchy: **Dale T  Willis → Willis Dimension Stone Inc → AMERICAN BLUE**

- 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

- **controller_controls_mine:** Marshall B  Mercer → AMERICAN BLUE; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Galaxy Granite Company → AMERICAN BLUE; 1979-01-01 to 1983-08-30; source msha-controller-operator-history
- **controller_controls_operator:** Marshall B  Mercer → Galaxy Granite Company; 1979-01-01 to 1983-08-30; source msha-controller-operator-history
- **controller_controls_mine:** F Browne Gregg Trust → AMERICAN BLUE; 1981-01-05 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Granite Panelwall Company → AMERICAN BLUE; 1983-08-31 to 1991-01-28; source msha-controller-operator-history
- **controller_controls_operator:** F Browne Gregg Trust → Granite Panelwall Company; 1983-08-31 to 1991-01-28; source msha-controller-operator-history
- **operator_operates_mine:** Willis Dimension Stone Inc → AMERICAN BLUE; 1991-01-29 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Dale T  Willis → AMERICAN BLUE; 1991-01-29 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Dale T  Willis → Willis Dimension Stone Inc; 1991-01-29 to current/open; source msha-controller-operator-history