# Relationship history for MSHA mine 4102390

Current hierarchy: **Schwartz San Louis → Quality Sand & Gravel → Quality Sand & Gravel**

- 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:** Martinez Sand & Gravel → Quality Sand & Gravel; 1950-01-01 to 1982-03-31; source msha-controller-operator-history
- **controller_controls_mine:** Martinez Humberto → Quality Sand & Gravel; 1950-01-01 to 1982-03-31; source msha-controller-operator-history
- **controller_controls_operator:** Martinez Humberto → Martinez Sand & Gravel; 1950-01-01 to 1982-03-31; source msha-controller-operator-history
- **operator_operates_mine:** Quality Sand & Gravel → Quality Sand & Gravel; 1982-04-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Schwartz San Louis → Quality Sand & Gravel; 1982-04-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Schwartz San Louis → Quality Sand & Gravel; 1982-04-01 to current/open; source msha-controller-operator-history