# Relationship history for MSHA mine 1103209

Current hierarchy: **Gregory K  Arnett → Black Nugget LLC → North Grindstone 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: 2026-10-13T11:19:05.459773+00:00

## Valid-time edges

- **operator_operates_mine:** PRO Mining LLC → North Grindstone Mine; 2008-11-26 to 2009-02-19; source msha-controller-operator-history
- **controller_controls_mine:** Philip R  Ott → North Grindstone Mine; 2008-11-26 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Philip R  Ott → PRO Mining LLC; 2008-11-26 to 2009-02-19; source msha-controller-operator-history
- **operator_operates_mine:** Black Nugget LLC → North Grindstone Mine; 2009-02-20 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Gregory K  Arnett → North Grindstone Mine; 2009-02-20 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Gregory K  Arnett → Black Nugget LLC; 2009-02-20 to current/open; source msha-controller-operator-history