# Relationship history for MSHA mine 0900991

Current hierarchy: **Kurt M  Swenson → Royalty Granite Corp → Continental 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

- **controller_controls_mine:** Coggins Industries Inc → Continental Blue Quarry; 1979-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Continental Granite Inc → Continental Blue Quarry; 1986-10-01 to 1992-01-27; source msha-controller-operator-history
- **controller_controls_operator:** Coggins Industries Inc → Continental Granite Inc; 1986-10-01 to 1992-01-27; source msha-controller-operator-history
- **operator_operates_mine:** Royalty Granite Corp → Continental Blue Quarry; 1992-01-28 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Kurt M  Swenson → Continental Blue Quarry; 1992-01-28 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Kurt M  Swenson → Royalty Granite Corp; 1992-01-28 to current/open; source msha-controller-operator-history