# Relationship history for MSHA mine 2901161

Current hierarchy: **Buchmeier William M → Oro Mountain Mining Corp → Silica Queen**

- 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:** Buchmeier William M → Silica Queen; 1987-06-15 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Oro Mountain Mining Corp → Silica Queen; 1987-10-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Buchmeier William M → Oro Mountain Mining Corp; 1987-10-01 to current/open; source msha-controller-operator-history