# Relationship history for MSHA mine 0504185

Current hierarchy: **Burnco Rock Products Ltd → BURNCO → POWERSCREEN CHIEFTAIN**

- 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

- **operator_operates_mine:** Tectonic Construction Company → POWERSCREEN CHIEFTAIN; 1986-10-01 to 1996-07-25; source msha-controller-operator-history
- **controller_controls_mine:** Lowdermilk Robert H → POWERSCREEN CHIEFTAIN; 1986-10-01 to 1996-07-25; source msha-controller-operator-history
- **controller_controls_operator:** Lowdermilk Robert H → Tectonic Construction Company; 1986-10-01 to 1996-07-25; source msha-controller-operator-history
- **controller_controls_mine:** George W  Hall et al → POWERSCREEN CHIEFTAIN; 1988-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Hall-Irwin Construction Company → POWERSCREEN CHIEFTAIN; 1996-07-26 to 2013-02-12; source msha-controller-operator-history
- **controller_controls_operator:** George W  Hall et al → Hall-Irwin Construction Company; 1996-07-26 to 2013-02-12; source msha-controller-operator-history
- **controller_controls_mine:** Scott  Masi et al → POWERSCREEN CHIEFTAIN; 2009-02-13 to 2017-02-26; source msha-controller-operator-history
- **operator_operates_mine:** BURNCO → POWERSCREEN CHIEFTAIN; 2013-02-13 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Scott  Masi et al → BURNCO; 2013-02-13 to 2017-02-26; source msha-controller-operator-history
- **controller_controls_operator:** Bret  Hall et al → BURNCO; 2013-02-13 to 2017-02-26; source msha-controller-operator-history
- **controller_controls_mine:** Burnco Rock Products Ltd → POWERSCREEN CHIEFTAIN; 2017-02-27 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Burnco Rock Products Ltd → BURNCO; 2017-02-27 to current/open; source msha-controller-operator-history