Exhibit 5.1

September 7, 2012

Peabody Energy Corporation

701 Market Street

St. Louis, Missouri 63101

Ladies and Gentlemen:

We have acted as counsel to Peabody Energy Corporation, Delaware corporation (the “Company”), and to the guarantors listed on Schedule I hereto (the “Guarantors”) in connection with the Registration Statement on Form S-4 (the “Registration Statement”) filed by the Company and the Guarantors with the Securities and Exchange Commission (the “Commission”) under the Securities Act of 1933, as amended, relating to the issuance by the Company of $1,518,821,000 aggregate principal amount of 6.00% Senior Notes due 2018 and $1,339,644,000 aggregate principal amount of 6.25% Senior Notes due 2021 (collectively, the “Exchange Securities”) and the issuance by the Guarantors of guarantees (the “Guarantees”) with respect to the Exchange Securities. The Exchange Securities and the Guarantees will be issued under an indenture dated as of November 15, 2011 (the “Indenture”) among the Company, the Guarantors and U.S. Bank National Association, as trustee (the “Trustee”). The Exchange Securities will be offered by the Company in exchange for $1,518,821,000 aggregate principal amount of 6.00% Senior Notes due 2018 and $1,339,644,000 aggregate principal amount of 6.25% Senior Notes due 2021.

We have examined the Registration Statement and the Indenture (including the form of Exchange Security set forth therein), which has been filed with the Commission as an exhibit to the Registration Statement. We also have examined the originals, or duplicates or certified or conformed copies, of such records, agreements, documents and other instruments and have made

such other investigations as we have deemed relevant and necessary in connection with the opinions hereinafter set forth. As to questions of fact material to this opinion, we have relied upon certificates or comparable documents of public officials and of officers and representatives of the Company and the Guarantors.

In rendering the opinions set forth below, we have assumed the genuineness of all signatures, the legal capacity of natural persons, the authenticity of all documents submitted to us as originals, the conformity to original documents of all documents submitted to us as duplicates or certified or conformed copies and the authenticity of the originals of such latter documents. We also have assumed that the Indenture is the valid and legally binding obligation of the Trustee.

Based upon the foregoing, and subject to the qualifications, assumptions and limitations stated herein, we are of the opinion that:

1. When the Exchange Securities have been duly executed, authenticated, issued and delivered in accordance with the provisions of the Indenture upon the exchange, the Exchange Securities will constitute valid and legally binding obligations of the Company enforceable against the Company in accordance with their terms.

2. When (a) the Exchange Securities have been duly executed, authenticated, issued and delivered in accordance with the provisions of the Indenture upon the exchange and (b) the Guarantees have been duly issued, the Guarantees will constitute valid and legally binding obligations of the Guarantors enforceable against the Guarantors in accordance with their terms.

Our opinions set forth above are subject to (i) the effects of bankruptcy, insolvency, fraudulent conveyance, reorganization, moratorium and other similar laws relating to or affecting creditors’ rights generally, (ii) general equitable principles (whether considered in a proceeding in equity or at law) and (iii) an implied covenant of good faith and fair dealing.

Insofar as the opinions expressed herein relate to or are dependent upon matters governed by the law of the State of Indiana, we have relied upon the opinion of Jackson Kelly PLLC dated August 3, 2012. Insofar as the opinions expressed herein relate to or are dependent upon matters governed by the law of the State of Illinois, we have relied upon the opinion of Thompson Coburn LLP dated August 3, 2012.

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We do not express any opinion herein concerning any law other than the law of the State of New York, the Delaware General Corporation Law, the Delaware Limited Liability Company Act and, to the extent set forth herein, the law of the State of Indiana and the law of the State of Illinois.

We hereby consent to the filing of this opinion letter as Exhibit 5 to the Registration Statement and to the use of our name under the caption “Legal Matters” in the Prospectus included in the Registration Statement.

Very truly yours,

/s/ Simpson Thacher & Bartlett LLP

SIMPSON THACHER & BARTLETT LLP

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Schedule I

Name of Subsidiary	Jurisdiction of Formation
American Land Development, LLC	Delaware
American Land Holdings of Colorado, LLC	Delaware
American Land Holdings of Illinois, LLC	Delaware
American Land Holdings of Indiana, LLC	Delaware
American Land Holdings of Kentucky, LLC	Delaware
American Land Holdings of West Virginia, LLC	Delaware
Arid Operations, Inc.	Delaware
Big Sky Coal Company	Delaware
BTU Western Resources, Inc.	Delaware
Caballo Grande, LLC	Delaware
Caseyville Dock Company, LLC	Delaware
Central States Coal Reserves of Illinois, LLC	Delaware
Central States Coal Reserves of Indiana, LLC	Delaware
Coal Reserve Holding Limited Liability Company No. 1	Delaware
COALSALES II, LLC	Delaware
Colorado Yampa Coal Company	Delaware
Conservancy Resources, LLC	Delaware
Cottonwood Land Company	Delaware
Cyprus Creek Land Company	Delaware
Cyprus Creek Land Resources, LLC	Delaware
Dyson Creek Coal Company, LLC	Delaware
Dyson Creek Mining Company, LLC	Delaware
El Segundo Coal Company, LLC	Delaware
Elkland Holdings, LLC	Delaware
Gallo Finance Company	Delaware
Gold Fields Chile, LLC	Delaware
Gold Fields Mining, LLC	Delaware
Gold Fields Ortiz, LLC	Delaware
Hayden Gulch Terminal, LLC	Delaware
Highwall Mining Services Company	Delaware
Hillside Recreational Lands, LLC	Delaware
HMC Mining, LLC	Delaware
Independence Material Handling, LLC	Delaware
James River Coal Terminal, LLC	Delaware
Juniper Coal Company	Delaware
Kayenta Mobile Home Park, Inc.	Delaware
Kentucky Syngas, LLC	Delaware
Lively Grove Energy, LLC	Delaware
Lively Grove Energy Partners, LLC	Delaware
Marigold Electricity, LLC	Delaware

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Midwest Coal Acquisition Corp.	Delaware
Midwest Coal Reserves of Illinois, LLC	Delaware
Midwest Coal Reserves of Indiana, LLC	Delaware
Moffat County Mining, LLC	Delaware
Mustang Energy Company, LLC	Delaware
New Mexico Coal Resources, LLC	Delaware
Pacific Export Resources, LLC	Delaware
Peabody America, Inc.	Delaware
Peabody Archveyor, LLC	Delaware
Peabody Bear Run Mining, LLC	Delaware
Peabody Bear Run Services, LLC	Delaware
Peabody Caballo Mining, LLC	Delaware
Peabody Cardinal Gasification, LLC	Delaware
Peabody COALSALES, LLC	Delaware
Peabody COALTRADE International (CTI), LLC	Delaware
Peabody COALTRADE, LLC	Delaware
Peabody Colorado Operations, LLC	Delaware
Peabody Colorado Services, LLC	Delaware
Peabody Coulterville Mining, LLC	Delaware
Peabody Development Company, LLC	Delaware
Peabody Electricity, LLC	Delaware
Peabody Employment Services, LLC	Delaware
Peabody Energy Generation Holding Company	Delaware
Peabody Energy Investments, Inc.	Delaware
Peabody Energy Solutions, Inc.	Delaware
Peabody Gateway North Mining, LLC	Delaware
Peabody Gateway Services, LLC	Delaware
Peabody Holding Company, LLC	Delaware
Peabody Illinois Services, LLC	Delaware
Peabody Indiana Services, LLC	Delaware
Peabody International Investments, Inc.	Delaware
Peabody International Services, Inc.	Delaware
Peabody Investments Corp.	Delaware
Peabody Midwest Management Services, LLC	Delaware
Peabody Midwest Operations, LLC	Delaware
Peabody Midwest Services, LLC	Delaware
Peabody Natural Gas, LLC	Delaware
Peabody Natural Resources Company	Delaware
Peabody New Mexico Services, LLC	Delaware
Peabody Operations Holding, LLC	Delaware
Peabody Powder River Mining, LLC	Delaware
Peabody Powder River Operations, LLC	Delaware
Peabody Powder River Services, LLC	Delaware
Peabody PowerTree Investments, LLC	Delaware

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Peabody Recreational Lands, LLC	Delaware
Peabody Rocky Mountain Management Services, LLC	Delaware
Peabody Rocky Mountain Services, LLC	Delaware
Peabody Sage Creek Mining, LLC	Delaware
Peabody School Creek Mining, LLC	Delaware
Peabody Services Holdings, LLC	Delaware
Peabody Southwest, LLC	Delaware
Peabody Southwestern Coal Company	Delaware
Peabody Terminal Holding Company, Inc.	Delaware
Peabody Terminals, LLC	Delaware
Peabody Trout Creek Reservoir LLC	Delaware
Peabody Twentymile Mining, LLC	Delaware
Peabody Venezuela Coal Corp.	Delaware
Peabody Venture Fund, LLC	Delaware
Peabody-Waterside Development, LLC	Delaware
Peabody Western Coal Company	Delaware
Peabody Wild Boar Mining, LLC	Delaware
Peabody Wild Boar Services, LLC	Delaware
Peabody Williams Fork Mining, LLC	Delaware
Peabody Wyoming Gas, LLC	Delaware
Peabody Wyoming Services, LLC	Delaware
PEC Equipment Company, LLC	Delaware
Point Pleasant Dock Company, LLC	Delaware
Pond River Land Company	Delaware
Porcupine Production, LLC	Delaware
Porcupine Transportation, LLC	Delaware
Riverview Terminal Company	Delaware
Sage Creek Holdings, LLC	Delaware
School Creek Coal Resources, LLC	Delaware
Seneca Coal Company, LLC	Delaware
Shoshone Coal Corporation	Delaware
Star Lake Energy Company, L.L.C.	Delaware
Thoroughbred Generating Company, LLC	Delaware
Thoroughbred Mining Company, LLC	Delaware
Twentymile Coal, LLC	Delaware
West Roundup Resources, LLC	Delaware
Big Ridge, Inc.	Illinois
Black Hills Mining Company, LLC	Illinois
Century Mineral Resources, Inc.	Illinois
Illinois Land Holdings, LLC	Illinois
Midco Supply and Equipment Corporation	Illinois
Falcon Coal Company, LLC	Indiana
Peabody Arclar Mining, LLC	Indiana
Peabody Midwest Mining, LLC	Indiana
Sugar Camp Properties, LLC	Indiana

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