# Relationship history for MSHA mine 0404235

Current hierarchy: **Cimenteries Cbr Cementbedrijven → Calaveras Portland Cement Company → Quatal Canyon Gypsum 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:** Monolith Portland Cement Company → Quatal Canyon Gypsum Quarry; 1950-01-01 to 1989-03-30; source msha-controller-operator-history
- **controller_controls_mine:** Monolith Portland Cement Company → Quatal Canyon Gypsum Quarry; 1950-01-01 to 1989-03-30; source msha-controller-operator-history
- **controller_controls_operator:** Monolith Portland Cement Company → Monolith Portland Cement Company; 1950-01-01 to 1989-03-30; source msha-controller-operator-history
- **operator_operates_mine:** Calaveras Portland Cement Company → Quatal Canyon Gypsum Quarry; 1989-03-31 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Cimenteries Cbr Cementbedrijven → Quatal Canyon Gypsum Quarry; 1989-03-31 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Cimenteries Cbr Cementbedrijven → Calaveras Portland Cement Company; 1989-03-31 to current/open; source msha-controller-operator-history