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                                                                     EXHIBIT 5.1
 
   
                                                                January 12, 1998
    
 
Anker Coal Group, Inc.
2708 Cranberry Square
Morgantown, West Virginia 26505
 
Ladies and Gentlemen:
 
     We have acted as special counsel for Anker Coal Group, Inc., a Delaware
corporation (the "Company"), in connection with the Registration Statement on
Form S-4 (the "Registration Statement") filed by the Company with the Securities
and Exchange Commission (the "Commission") under the Securities Act of 1933, as
amended (the "Securities Act"), relating to the issuance by the Company of
$125,000,000 aggregate principal amount of its 9 3/4% Series B Senior Notes due
2007 (the "Exchange Notes"), guaranteed (the "Guarantees") on a senior basis by
the entities listed on Schedule A hereto (collectively, the "Guarantors"). The
Exchange Notes are to be offered by the Company in exchange for (the "Exchange")
$125,000,000 aggregate principal amount of its outstanding 9 3/4% Senior Notes
due 2007 (the "Notes"). The Notes have been, and the Exchange Notes will be,
issued under an Indenture dated as of September 25, 1997 (the "Indenture")
between the Company, the Guarantors and Marine Midland Bank, as Trustee (the
"Trustee").
 
     We have examined the Registration Statement and the Indenture, which has
been filed with the Commission as an Exhibit to the Registration Statement. In
addition, we have examined, and have relied as to matters of fact upon, the
originals or copies, certified or otherwise identified to our satisfaction, of
such corporate records, agreements, documents and other instruments and such
certificates or comparable documents of public officials and of officers and
representatives of the Company, and have made such other and further
investigations, as we have deemed relevant and necessary as a basis for the
opinion hereinafter set forth.
 
     In such examination, we have assumed the genuineness of all signatures, the
legal capacity of natural persons, the authenticity of all documents submitted
to us as originals and the conformity to original documents of all documents
submitted to us as certified or photostatic copies, and the authenticity of the
originals of such latter documents.
 
     Based upon the foregoing, and subject to the qualifications and limitations
stated herein, we are of the opinion that:
 
   
          (i) assuming the Indenture has been duly authorized and validly
     executed and delivered by the parties thereto, when the Exchange Notes have
     been duly executed, authenticated, issued and delivered in accordance with
     the provisions of the Indenture upon the Exchange, the Exchange Notes will
     constitute valid and legally binding obligations of the Company,
     enforceable against the Company in accordance with their terms; and
    
 
   
          (ii) assuming the Indenture has been duly authorized and validly
     executed and delivered by the parties thereto, when (1) the Board of
     Directors of each Guarantor, a duly constituted and acting committee
     thereof or duly authorized officers thereof have taken all necessary
     corporate action to approve the issuance and terms of such Guarantor's
     Guarantee and (2) the Exchange Notes and the Guarantees endorsed thereon
     have been duly executed, authenticated, issued and delivered in accordance
     with the provisions of the Indenture upon the Exchange, each Guarantor's
     Guarantee will constitute a valid and legally binding obligation of such
     Guarantor, enforceable against such Guarantor in accordance with its terms.
    
 
   
     Our opinions set forth in paragraphs (i) and (ii) are subject to the
effects of bankruptcy, insolvency, fraudulent conveyance, reorganization,
moratorium and other similar laws relating to or affecting creditors' rights
generally, general equitable principles (whether considered in a proceeding in
equity or at law) and an implied covenant of good faith and fair dealing. We
note that the Indenture is governed by the law of the State of New York.
    
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     We are members of the Bar of the State of New York and we do not express
any opinion herein concerning any law other than the law of the State of New
York and the federal law of the United States.
 
     We hereby consent to the use of this opinion as an Exhibit to the
Registration Statement and to the reference to our firm under the caption "Legal
Matters" in the Prospectus included therein.
 
                                          Very truly yours,
 
                                          SIMPSON THACHER & BARTLETT
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                                   SCHEDULE A
 


                                                                                   STATE OF
                                   COMPANY                                      INCORPORATION
- ------------------------------------------------------------------------------  --------------
                                                                             
Anker Group, Inc.                                                               Delaware
Anker Energy Corporation                                                        Delaware
Bronco Mining Company, Inc.                                                     West Virginia
Anker Power Services, Inc.                                                      West Virginia
Anker West Virginia Mining Company, Inc.                                        West Virginia
Juliana Mining Company, Inc.                                                    West Virginia
King Knob Coal Co., Inc.                                                        West Virginia
Vantrans, Inc.                                                                  Delaware
Melrose Coal Company, Inc.                                                      West Virginia
Marine Coal Sales Company                                                       Delaware
Hawthorne Coal Company, Inc.                                                    West Virginia
Upshur Property, Inc.                                                           Delaware
Heather Glen Resources, Inc.                                                    West Virginia
New Allegheny Land Holding Company, Inc.                                        West Virginia
Patriot Mining Company, Inc.                                                    West Virginia
Vindex Energy Corporation                                                       West Virginia
Anker Virginia Mining Company, Inc.                                             Virginia