# Relationship history for MSHA mine 1500213

Current hierarchy: **CRH PLC → Mountain Aggregates Inc → Elkhorn  Stone**

- 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:** Elkhorn Stone Company → Elkhorn  Stone; 1950-01-01 to 1978-12-31; source msha-controller-operator-history
- **controller_controls_mine:** Medusa Corp → Elkhorn  Stone; 1950-01-01 to 1978-12-31; source msha-controller-operator-history
- **controller_controls_operator:** Medusa Corp → Elkhorn Stone Company; 1950-01-01 to 1978-12-31; source msha-controller-operator-history
- **operator_operates_mine:** Elkhorn Stone Company → Elkhorn  Stone; 1979-01-01 to 1982-10-10; source msha-controller-operator-history
- **controller_controls_mine:** Crane Company → Elkhorn  Stone; 1979-01-01 to 1982-10-10; source msha-controller-operator-history
- **controller_controls_operator:** Crane Company → Elkhorn Stone Company; 1979-01-01 to 1982-10-10; source msha-controller-operator-history
- **operator_operates_mine:** Elkhorn Stone Inc → Elkhorn  Stone; 1982-10-11 to 2006-01-22; source msha-controller-operator-history
- **controller_controls_mine:** Steve L  Lawson et al → Elkhorn  Stone; 1982-10-11 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Steve L  Lawson et al → Elkhorn Stone Inc; 1982-10-11 to 2006-01-22; source msha-controller-operator-history
- **operator_operates_mine:** Mountain Aggregates Inc → Elkhorn  Stone; 2006-01-23 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** CRH PLC → Elkhorn  Stone; 2006-01-23 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** CRH PLC → Mountain Aggregates Inc; 2006-01-23 to current/open; source msha-controller-operator-history