# Relationship history for MSHA mine 1102051

Current hierarchy: **Covia Holdings LLC → Covia Specialty Minerals, Inc. → Tamms Plant**

- 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:** Tammsco Inc → Tamms Plant; 1950-01-01 to 1984-03-14; source msha-controller-operator-history
- **controller_controls_mine:** John  Norton → Tamms Plant; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** John  Norton → Tammsco Inc; 1950-01-01 to 1984-03-14; source msha-controller-operator-history
- **controller_controls_mine:** S C R-Sibelco Nv et al → Tamms Plant; 1950-01-01 to 2020-12-31; source msha-controller-operator-history
- **operator_operates_mine:** Tammsco Inc → Tamms Plant; 1984-03-15 to 1987-05-31; source msha-controller-operator-history
- **controller_controls_mine:** Avitar Industries Inc → Tamms Plant; 1984-03-15 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Avitar Industries Inc → Tammsco Inc; 1984-03-15 to 1987-05-31; source msha-controller-operator-history
- **controller_controls_mine:** S C R-Sibelco Nv et al → Tamms Plant; 1986-06-30 to 2020-12-31; source msha-controller-operator-history
- **operator_operates_mine:** Unimin Specialty Minerals, Inc. → Tamms Plant; 1987-06-01 to 2016-02-24; source msha-controller-operator-history
- **controller_controls_operator:** S C R-Sibelco Nv et al → Unimin Specialty Minerals, Inc.; 1987-06-01 to 2016-02-24; source msha-controller-operator-history
- **operator_operates_mine:** Unimin Corporation → Tamms Plant; 2016-02-25 to 2018-06-26; source msha-controller-operator-history
- **controller_controls_operator:** S C R-Sibelco Nv et al → Unimin Corporation; 2016-02-25 to 2018-06-26; source msha-controller-operator-history
- **operator_operates_mine:** Covia Specialty Minerals, Inc. → Tamms Plant; 2018-06-27 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** S C R-Sibelco Nv et al → Covia Specialty Minerals, Inc.; 2018-06-27 to 2020-12-31; source msha-controller-operator-history
- **controller_controls_mine:** Covia Holdings LLC → Tamms Plant; 2021-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Covia Holdings LLC → Unimin Specialty Minerals, Inc.; 2021-01-01 to 2016-02-24; source msha-controller-operator-history
- **controller_controls_operator:** Covia Holdings LLC → Unimin Corporation; 2021-01-01 to 2018-06-26; source msha-controller-operator-history
- **controller_controls_operator:** Covia Holdings LLC → Covia Specialty Minerals, Inc.; 2021-01-01 to current/open; source msha-controller-operator-history