# Relationship history for MSHA mine 3003023

Current hierarchy: **Graymont Ltd → Potsdam Stone & Concrete-Div/Graystone Mtrls Inc → Cold Brook**

- 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:** Graymont Ltd → Cold Brook; 1986-04-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Potsdam Stone & Concrete-Div/Graystone Mtrls Inc → Cold Brook; 1991-10-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Graymont Ltd → Potsdam Stone & Concrete-Div/Graystone Mtrls Inc; 1991-10-01 to current/open; source msha-controller-operator-history