# Relationship history for MSHA mine 2800021

Current hierarchy: **John L  Silvi; Laurence J  Silvi II → Gibralter Rock Inc. T-A Gibraltar Rock, Belle Mead → Belle Mead Quarry**

- 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

- **operator_operates_mine:** Minnesota Mining & Manufacturing Company → Belle Mead Quarry; 1950-01-01 to 2009-07-22; source msha-controller-operator-history
- **controller_controls_mine:** Minnesota Mining & Manufacturing Company → Belle Mead Quarry; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Minnesota Mining & Manufacturing Company → Minnesota Mining & Manufacturing Company; 1950-01-01 to 2009-07-22; source msha-controller-operator-history
- **controller_controls_mine:** John L  Silvi  Et Al → Belle Mead Quarry; 2009-06-22 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Gibralter Rock Inc. T-A Gibraltar Rock, Belle Mead → Belle Mead Quarry; 2009-07-23 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** John L  Silvi  Et Al → Gibralter Rock Inc. T-A Gibraltar Rock, Belle Mead; 2009-07-23 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Laurence J  Silvi II  Et Al → Gibralter Rock Inc. T-A Gibraltar Rock, Belle Mead; 2009-07-23 to current/open; source msha-controller-operator-history