# Relationship history for MSHA mine 4201500

Current hierarchy: **Thyssen Mining Construction Inc & Hydrocarbon Mini → Hydrocarbon Resources Company → Black Gnat 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:** Tarmac Inc → Black Gnat Mine; 1978-03-09 to 1981-06-30; source msha-controller-operator-history
- **controller_controls_mine:** Green Robert → Black Gnat Mine; 1978-03-09 to 1981-06-30; source msha-controller-operator-history
- **controller_controls_operator:** Green Robert → Tarmac Inc; 1978-03-09 to 1981-06-30; source msha-controller-operator-history
- **controller_controls_mine:** Thyssen Mining Construction Inc & Hydrocarbon Mini → Black Gnat Mine; 1981-05-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Hydrocarbon Resources Company → Black Gnat Mine; 1981-07-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Thyssen Mining Construction Inc & Hydrocarbon Mini → Hydrocarbon Resources Company; 1981-07-01 to current/open; source msha-controller-operator-history