# Relationship history for MSHA mine 3600125

Current hierarchy: **Elementia Materiales → Keystone Cement Company → KEYSTONE CEMENT COMPANY**

- 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:** Keystone Cement Company → KEYSTONE CEMENT COMPANY; 1950-01-01 to 1994-10-05; source msha-controller-operator-history
- **controller_controls_mine:** Giant Group Ltd → KEYSTONE CEMENT COMPANY; 1950-01-01 to 1994-10-05; source msha-controller-operator-history
- **controller_controls_operator:** Giant Group Ltd → Keystone Cement Company; 1950-01-01 to 1994-10-05; source msha-controller-operator-history
- **operator_operates_mine:** Keystone Cement Company → KEYSTONE CEMENT COMPANY; 1994-10-06 to 1999-12-09; source msha-controller-operator-history
- **controller_controls_mine:** Giant Cement Holding Inc → KEYSTONE CEMENT COMPANY; 1994-10-06 to 1999-12-09; source msha-controller-operator-history
- **controller_controls_operator:** Giant Cement Holding Inc → Keystone Cement Company; 1994-10-06 to 1999-12-09; source msha-controller-operator-history
- **operator_operates_mine:** Keystone Cement Company → KEYSTONE CEMENT COMPANY; 1999-12-10 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Cementos Portland Valderrivas S A → KEYSTONE CEMENT COMPANY; 1999-12-10 to 2016-10-25; source msha-controller-operator-history
- **controller_controls_operator:** Cementos Portland Valderrivas S A → Keystone Cement Company; 1999-12-10 to 2016-10-25; source msha-controller-operator-history
- **controller_controls_mine:** Elementia Materiales → KEYSTONE CEMENT COMPANY; 2016-10-26 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Elementia Materiales → Keystone Cement Company; 2016-10-26 to current/open; source msha-controller-operator-history