# Relationship history for MSHA mine 4104575

Current hierarchy: **John R  Weisman → Colorado Materials LTD → Colorado Materials - Sand Screen #2**

- 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:** John R  Weisman → Colorado Materials - Sand Screen #2; 1980-10-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Colorado Materials LTD → Colorado Materials - Sand Screen #2; 2006-02-08 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** John R  Weisman → Colorado Materials LTD; 2006-02-08 to current/open; source msha-controller-operator-history