# Relationship history for MSHA mine 4503257

Current hierarchy: **Imasco Minerals Inc → Nanome Aggregates Inc → Pearl Grey 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:** Imasco Minerals Inc → Pearl Grey Quarry; 1991-07-19 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Nanome Aggregates Inc → Pearl Grey Quarry; 1991-09-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Imasco Minerals Inc → Nanome Aggregates Inc; 1991-09-01 to current/open; source msha-controller-operator-history