# Relationship history for MSHA mine 0900896

Current hierarchy: **Peter T  De Kok → Gran-Quartz International Inc → Old Harper 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

- **controller_controls_mine:** Horace K  Harper → Old Harper Quarry; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Harpers Quarry Inc → Old Harper Quarry; 1979-01-01 to 1981-05-31; source msha-controller-operator-history
- **controller_controls_operator:** Horace K  Harper → Harpers Quarry Inc; 1979-01-01 to 1981-05-31; source msha-controller-operator-history
- **operator_operates_mine:** Gran-Quartz International Inc → Old Harper Quarry; 1981-06-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Peter T  De Kok → Old Harper Quarry; 1981-06-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Peter T  De Kok → Gran-Quartz International Inc; 1981-06-01 to current/open; source msha-controller-operator-history