# Relationship history for MSHA mine 3101955

Current hierarchy: **Imerys S A; Norsk Mineral AS → The Quartz Corp USA → KT Mica**

- 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

- **controller_controls_mine:** USG Corporation → KT Mica; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** United States Gypsum Company → KT Mica; 1983-03-01 to 2020-01-01; source msha-controller-operator-history
- **controller_controls_operator:** USG Corporation → United States Gypsum Company; 1983-03-01 to 2020-01-01; source msha-controller-operator-history
- **controller_controls_mine:** Imerys S A → KT Mica; 2001-03-28 to 2011-03-31; source msha-controller-operator-history
- **controller_controls_mine:** Imerys S A  et al → KT Mica; 2011-04-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** The Quartz Corp USA → KT Mica; 2020-01-02 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Imerys S A  et al → The Quartz Corp USA; 2020-01-02 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Norsk Mineral AS  et al → The Quartz Corp USA; 2020-01-02 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Imerys S A → The Quartz Corp USA; 2020-01-02 to 2011-03-31; source msha-controller-operator-history