# Relationship history for MSHA mine 4502627

Current hierarchy: **Harbor Resources → Cascade Pumice Inc → Cmi Portable Plant**

- 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:** Graystone Corp → Cmi Portable Plant; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Graystone Of Olympia → Cmi Portable Plant; 1979-01-01 to 1986-01-29; source msha-controller-operator-history
- **controller_controls_operator:** Graystone Corp → Graystone Of Olympia; 1979-01-01 to 1986-01-29; source msha-controller-operator-history
- **controller_controls_mine:** Harbor Resources → Cmi Portable Plant; 1985-05-15 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Cascade Pumice Inc → Cmi Portable Plant; 1986-01-30 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Harbor Resources → Cascade Pumice Inc; 1986-01-30 to current/open; source msha-controller-operator-history