# Relationship history for MSHA mine 2900608

Current hierarchy: **Oglebay Norton Company → Oglebay Norton Specialty Minerals Incorporated → U S Hill Mine**

- 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:** Mineral Industrial Commodities Of America Inc → U S Hill Mine; 1950-01-01 to 1990-07-22; source msha-controller-operator-history
- **controller_controls_mine:** Mineral Industrial Commodities Of America → U S Hill Mine; 1950-01-01 to 1990-07-22; source msha-controller-operator-history
- **controller_controls_operator:** Mineral Industrial Commodities Of America → Mineral Industrial Commodities Of America Inc; 1950-01-01 to 1990-07-22; source msha-controller-operator-history
- **controller_controls_mine:** Franklin Industries Inc → U S Hill Mine; 1950-01-01 to 2006-11-30; source msha-controller-operator-history
- **operator_operates_mine:** Franklin Industrial Minerals → U S Hill Mine; 1990-07-23 to 1999-11-30; source msha-controller-operator-history
- **controller_controls_operator:** Franklin Industries Inc → Franklin Industrial Minerals; 1990-07-23 to 1999-11-30; source msha-controller-operator-history
- **operator_operates_mine:** Oglebay Norton Specialty Minerals Incorporated → U S Hill Mine; 1999-12-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Oglebay Norton Company → U S Hill Mine; 1999-12-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Oglebay Norton Company → Oglebay Norton Specialty Minerals Incorporated; 1999-12-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Lhoist Group → U S Hill Mine; 2006-12-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Lhoist Group → Franklin Industrial Minerals; 2006-12-01 to 1999-11-30; source msha-controller-operator-history