# Relationship history for MSHA mine 3100673

Current hierarchy: **S C R-Sibelco Nv → Sibelco North America, Inc → Quartz / Feldspar Operation**

- 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:** International Minerals & Chemical Corp → Quartz / Feldspar Operation; 1950-01-01 to 1986-12-03; source msha-controller-operator-history
- **controller_controls_mine:** IMC Global Inc → Quartz / Feldspar Operation; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** IMC Global Inc → International Minerals & Chemical Corp; 1950-01-01 to 1986-12-03; source msha-controller-operator-history
- **controller_controls_mine:** S C R-Sibelco Nv et al → Quartz / Feldspar Operation; 1950-01-01 to 2020-12-31; source msha-controller-operator-history
- **operator_operates_mine:** Unimin Corp → Quartz / Feldspar Operation; 1986-12-04 to 2018-05-31; source msha-controller-operator-history
- **controller_controls_operator:** S C R-Sibelco Nv et al → Unimin Corp; 1986-12-04 to 2018-05-31; source msha-controller-operator-history
- **operator_operates_mine:** Sibelco North America, Inc → Quartz / Feldspar Operation; 2018-06-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** S C R-Sibelco Nv et al → Quartz / Feldspar Operation; 2018-06-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** S C R-Sibelco Nv et al → Sibelco North America, Inc; 2018-06-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Covia Holdings LLC → Quartz / Feldspar Operation; 2021-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Covia Holdings LLC → Unimin Corp; 2021-01-01 to 2018-05-31; source msha-controller-operator-history