---
schema_version: "secwatch.filing_event.v1"
accession: "0001710366-26-000034"
form_type: "8-K"
ticker: "CNR"
cik: "0001710366"
company_name: "Core Natural Resources, Inc."
filed_at: "2026-05-04T23:59:59+00:00"
generated_at: "2026-05-14T23:56:53.126053+00:00"
event_type: "regulatory"
sentiment: "negative"
materiality_score: 0.3
confidence: "high"
source: SEC EDGAR
---

# Core Natural Resources subsidiary receives imminent danger order at Mountaineer II mine for methane

## Summary
- Mingo Logan Coal LLC received a 107(a) order on April 29, 2026 at Mountaineer II mine in Logan County, WV.
- Methane levels exceeded 5.0% in intake entry crosscuts and ranged from 1.0% to 2.2% in the center.
- Mine personnel took prompt actions to alleviate the condition; MSHA terminated the order the same day.
- No injuries or illnesses resulted from the temporary methane accumulation incident.

## SEC filing metadata
- accession: 0001710366-26-000034
- form_type: 8-K
- ticker: CNR
- cik: 0001710366
- company_name: Core Natural Resources, Inc.
- filed_at: 2026-05-04T23:59:59+00:00
- event_type: regulatory
- sentiment: negative
- materiality_score: 0.3
- confidence: high
- sec_items: 1.04
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1710366/000171036626000034/0001710366-26-000034-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1710366/000171036626000034/cnr-20260429.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001710366-26-000034
- JSON: https://secwatch.observer/filing/0001710366-26-000034.json
- Plain text: https://secwatch.observer/filing/0001710366-26-000034.txt

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