# Relationship history for MSHA mine 2200415

Current hierarchy: **USS Holdings Inc → U.S. Silica Company, LLC → EP Engineered Clays Corporation**

- 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

- **controller_controls_mine:** Engelhard Corp → EP Engineered Clays Corporation; 1950-01-01 to 2006-07-31; source msha-controller-operator-history
- **operator_operates_mine:** Filtrol Corp → EP Engineered Clays Corporation; 1950-01-01 to 1981-03-31; source msha-controller-operator-history
- **controller_controls_mine:** U S Filter Corp → EP Engineered Clays Corporation; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** U S Filter Corp → Filtrol Corp; 1950-01-01 to 1981-03-31; source msha-controller-operator-history
- **operator_operates_mine:** Filtrol Corp → EP Engineered Clays Corporation; 1981-04-01 to 1981-12-14; source msha-controller-operator-history
- **controller_controls_mine:** Ashland Inc → EP Engineered Clays Corporation; 1981-04-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Ashland Inc → Filtrol Corp; 1981-04-01 to 1981-12-14; source msha-controller-operator-history
- **operator_operates_mine:** Filtrol Corp → EP Engineered Clays Corporation; 1981-12-15 to 1983-09-30; source msha-controller-operator-history
- **controller_controls_mine:** Kaiser Aluminum & Chemical Corp → EP Engineered Clays Corporation; 1981-12-15 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Kaiser Aluminum & Chemical Corp → Filtrol Corp; 1981-12-15 to 1983-09-30; source msha-controller-operator-history
- **operator_operates_mine:** Harshaw/Filtrol Partnership → EP Engineered Clays Corporation; 1983-10-01 to 1988-08-31; source msha-controller-operator-history
- **controller_controls_mine:** Kaiser Aluminum & Chemical Corp et al → EP Engineered Clays Corporation; 1983-10-01 to 1988-08-31; source msha-controller-operator-history
- **controller_controls_operator:** Kaiser Aluminum & Chemical Corp et al → Harshaw/Filtrol Partnership; 1983-10-01 to 1988-08-31; source msha-controller-operator-history
- **operator_operates_mine:** BASF Catalysts LLC → EP Engineered Clays Corporation; 1988-09-01 to 2011-12-06; source msha-controller-operator-history
- **controller_controls_operator:** Engelhard Corp → BASF Catalysts LLC; 1988-09-01 to 2006-07-31; source msha-controller-operator-history
- **controller_controls_mine:** USS Holdings Inc → EP Engineered Clays Corporation; 1996-03-09 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** BASF SE → EP Engineered Clays Corporation; 2006-08-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** BASF SE → BASF Catalysts LLC; 2006-08-01 to 2011-12-06; source msha-controller-operator-history
- **controller_controls_mine:** BASF SE → EP Engineered Clays Corporation; 2007-03-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** BASF Corporation → EP Engineered Clays Corporation; 2011-12-07 to 2017-07-16; source msha-controller-operator-history
- **controller_controls_operator:** BASF SE → BASF Corporation; 2011-12-07 to 2017-07-16; source msha-controller-operator-history
- **operator_operates_mine:** EP Engineered Clays Corporation → EP Engineered Clays Corporation; 2017-07-17 to 2019-05-13; source msha-controller-operator-history
- **controller_controls_mine:** EP Management Corporation → EP Engineered Clays Corporation; 2017-07-17 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** EP Management Corporation → EP Engineered Clays Corporation; 2017-07-17 to 2019-05-13; source msha-controller-operator-history
- **operator_operates_mine:** U.S. Silica Company, LLC → EP Engineered Clays Corporation; 2019-05-14 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** USS Holdings Inc → U.S. Silica Company, LLC; 2019-05-14 to current/open; source msha-controller-operator-history