# Relationship history for MSHA mine 0503608

Current hierarchy: **Zanett Richard G → Zmk Mine Construction Inc → GRIZZLY BEAR MINE**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **operator_operates_mine:** Sundance Oil Company → GRIZZLY BEAR MINE; 1980-10-01 to 1989-05-07; source msha-controller-operator-history
- **controller_controls_mine:** Silver Caswell → GRIZZLY BEAR MINE; 1980-10-01 to 1989-05-07; source msha-controller-operator-history
- **controller_controls_operator:** Silver Caswell → Sundance Oil Company; 1980-10-01 to 1989-05-07; source msha-controller-operator-history
- **operator_operates_mine:** Zmk Mine Construction Inc → GRIZZLY BEAR MINE; 1989-05-08 to 1996-06-30; source msha-controller-operator-history
- **controller_controls_mine:** Zanett Richard G → GRIZZLY BEAR MINE; 1989-05-08 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Zanett Richard G → Zmk Mine Construction Inc; 1989-05-08 to 1996-06-30; source msha-controller-operator-history
- **operator_operates_mine:** Sunshine Precious Metals Inc → GRIZZLY BEAR MINE; 1996-07-01 to 1997-07-10; source msha-controller-operator-history
- **controller_controls_mine:** Savage Mining & Oil Co & Sunshine Precious Metals → GRIZZLY BEAR MINE; 1996-07-01 to 1997-07-10; source msha-controller-operator-history
- **controller_controls_operator:** Savage Mining & Oil Co & Sunshine Precious Metals → Sunshine Precious Metals Inc; 1996-07-01 to 1997-07-10; source msha-controller-operator-history
- **operator_operates_mine:** Zmk Mine Construction Inc → GRIZZLY BEAR MINE; 1997-07-11 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Zanett Richard G → Zmk Mine Construction Inc; 1997-07-11 to current/open; source msha-controller-operator-history