EXHIBIT 3.3 CERTIFICATE OF FORMATION OF ARCH WESTERN RESOURCES, LLC A Limited Liability Company FIRST: The name of the limited liability company is: Arch Western Resources, LLC SECOND: The address of the limited liability company's registered office in the State of Delaware is Corporation Trust Center, 1209 Orange Street, in the City of Wilmington, County of New Castle. The name of its registered agent at such address is The Corporation Trust Company. THE UNDERSIGNED, being the individual forming the limited liability company, has executed, signed and acknowledged this Certificate of Formation this 27th day of February, 1998. /s/ Miriam Rogers Singer ------------------------------ Name: Miriam Rogers Singer