# Relationship history for MSHA mine 4500983

Current hierarchy: **Hemphill Brothers Inc → Lane Mt. Silica Co. → Lane Mtn Silica Quarry & Mill**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **controller_controls_mine:** Hemphill Brothers Inc → Lane Mtn Silica Quarry & Mill; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Lane Mountain Silica Company → Lane Mtn Silica Quarry & Mill; 1950-01-01 to 1985-07-08; source msha-controller-operator-history
- **controller_controls_mine:** Martin Marietta Corp et al → Lane Mtn Silica Quarry & Mill; 1950-01-01 to 1985-07-08; source msha-controller-operator-history
- **controller_controls_operator:** Martin Marietta Corp et al → Lane Mountain Silica Company; 1950-01-01 to 1985-07-08; source msha-controller-operator-history
- **operator_operates_mine:** Hemphill Brothers Inc → Lane Mtn Silica Quarry & Mill; 1985-07-09 to 2013-01-08; source msha-controller-operator-history
- **controller_controls_operator:** Hemphill Brothers Inc → Hemphill Brothers Inc; 1985-07-09 to 2013-01-08; source msha-controller-operator-history
- **controller_controls_mine:** Hemphill Brothers Inc → Lane Mtn Silica Quarry & Mill; 2013-01-09 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Hemphill Brothers Inc → Lane Mountain Silica Company; 2013-01-09 to 1985-07-08; source msha-controller-operator-history
- **operator_operates_mine:** Lane Mt. Silica Co. → Lane Mtn Silica Quarry & Mill; 2013-01-09 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Hemphill Brothers Inc → Lane Mt. Silica Co.; 2013-01-09 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Martin Marietta Corp et al → Lane Mt. Silica Co.; 2013-01-09 to 1985-07-08; source msha-controller-operator-history