---
schema_version: "secwatch.filing_event.v1"
accession: "0001710366-25-000035"
form_type: "8-K"
ticker: "CNR"
cik: "0001710366"
company_name: "Core Natural Resources, Inc."
filed_at: "2025-12-18T23:59:59+00:00"
generated_at: "2026-05-16T12:45:40.346629+00:00"
event_type: "other_material"
sentiment: "positive"
materiality_score: 0.65
confidence: "high"
source: SEC EDGAR
---

# Core Natural Resources resumes longwall operations at Leer South mine; West Elk productivity normalizes

## Summary
- Leer South longwall restarted after being idle since Jan 13, 2025 due to combustion-related activity.
- Affected area permanently sealed; equipment (209 shields, shearer, etc.) recovered in good condition.
- West Elk mine now at consistent productivity levels following B-Seam transition; expects continued improvement.
- Company expects significant 2026 step-up from restart, better West Elk conditions, insurance recoveries, and merger synergies.

## SEC filing metadata
- accession: 0001710366-25-000035
- form_type: 8-K
- ticker: CNR
- cik: 0001710366
- company_name: Core Natural Resources, Inc.
- filed_at: 2025-12-18T23:59:59+00:00
- event_type: other_material
- sentiment: positive
- materiality_score: 0.65
- confidence: high
- sec_items: 7.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1710366/000171036625000035/0001710366-25-000035-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1710366/000171036625000035/cnr-20251218.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001710366-25-000035
- JSON: https://secwatch.observer/filing/0001710366-25-000035.json
- Plain text: https://secwatch.observer/filing/0001710366-25-000035.txt

This AI-assisted summary is a reading aid. Review the linked SEC EDGAR filing before relying on any specific claim.