FIFTEENTH SUPPLEMENTAL INDENTURE (6 7/8% Notes due 2013)

Exhibit 4.21

FIFTEENTH SUPPLEMENTAL INDENTURE
(6 7/8% Notes due 2013)

     FIFTEENTH SUPPLEMENTAL INDENTURE (this “Supplemental Indenture”), dated as of November 14, 2007, by and among the entities listed on Schedule I attached hereto (the “Guaranteeing Subsidiaries”), each being a subsidiary of Peabody Energy Corporation (or its permitted successor), a Delaware corporation (the “Company”), the Company, the other Subsidiary Guarantors (as defined in the Indenture referred to herein) and US Bank National Association, as Trustee under the Indenture referred to below (the “Trustee”).

WITNESSETH

     WHEREAS, the Company has heretofore executed and delivered to the Trustee an Indenture (the “Indenture”), dated as of March 21, 2003 providing for the issuance of an unlimited amount of 6 7/8% Notes due 2013 (the “Notes”), as supplemented by:

	•		First Supplemental Indenture, dated as of May 7, 2003;
	•		Second Supplemental Indenture, dated as of September 30, 2003;
	•		Third Supplemental Indenture, dated as of February 24, 2004;
	•		Fourth Supplemental Indenture, dated as of April 22, 2004;
	•		Fifth Supplemental Indenture, dated as of October 18, 2004;
	•		Sixth Supplemental Indenture, dated as of January 20, 2005;
	•		Seventh Supplemental Indenture, dated as of September 30, 2005;
	•		Eighth Supplemental Indenture, dated as of January 20, 2006;
	•		Ninth Supplemental Indenture, dated as of June 13, 2006;
	•		Tenth Supplemental Indenture, dated as of June 30, 2006;
	•		Eleventh Supplemental Indenture, dated as of September 29, 2006;
	•		Twelfth Supplemental Indenture, dated as of November 10, 2006;
	•		Thirteenth Supplemental Indenture, dated as of January 31, 2007; and
	•		Fourteenth Supplemental Indenture, dated as of June 14, 2007;

     WHEREAS, the Indenture provides that under certain circumstances the Guaranteeing Subsidiaries shall execute and deliver to the Trustee a supplemental indenture pursuant to which the Guaranteeing Subsidiaries shall unconditionally guarantee all of the Company’s Obligations under the Notes on the terms and conditions set forth herein (the “Subsidiary Guarantee”); and

     WHEREAS, pursuant to Section 9.01 of the Indenture, the Trustee is authorized to execute and deliver this Supplemental Indenture.

     NOW THEREFORE, in consideration of the foregoing and for other good and valuable consideration, the receipt of which is hereby acknowledged, the Guaranteeing Subsidiaries and the Trustee mutually covenant and agree for the equal and ratable benefit of the Holders of the Notes as follows:

     1. Capitalized Terms. Capitalized terms used herein without definition shall have the meanings assigned to them in the Indenture.

     2. Agreement to Guarantee. Each of the Guaranteeing Subsidiaries hereby agrees as follows:

(a)

Along with all Subsidiary Guarantors named in the Indenture, to jointly and severally Guarantee to each Holder of a Note authenticated and delivered by the

Trustee and to the Trustee and its successors and assigns, irrespective of the validity and enforceability of the Indenture, the Notes or the obligations of the Company hereunder or thereunder, that:

	(i)		the principal of and interest on the Notes will be promptly paid in full when due, whether at maturity, by acceleration, redemption or otherwise, and interest on the overdue principal of and interest on the Notes, if any, if lawful, and all other obligations of the Company to the Holders or the Trustee hereunder or thereunder will be promptly paid in full or performed, all in accordance with the terms hereof and thereof; and
	(ii)		in case of any extension of time of payment or renewal of any Notes or any of such other obligations, that same will be promptly paid in full when due or performed in accordance with the terms of the extension or renewal, whether at stated maturity, by acceleration or otherwise.

			Failing payment when due of any amount so guaranteed or any performance so guaranteed for whatever reason, the Subsidiary Guarantors shall be jointly and severally obligated to pay the same immediately. Each Subsidiary Guarantor agrees that this is a guarantee of payment and not a guarantee of collection.
	(b)		The obligations hereunder shall be joint and several and unconditional, irrespective of the validity or enforceability of the Notes or the obligations of the Company under the Indenture, the absence of any action to enforce the same, any waiver or consent by any Holder of the Notes with respect to any provisions hereof or thereof, the recovery of any judgment against the Company, any action to enforce the same or any other circumstance which might otherwise constitute a legal or equitable discharge or defense of a Subsidiary Guarantor.
	(c)		The following is hereby waived: diligence, presentment, demand of payment, filing of claims with a court in the event of insolvency or bankruptcy of the Company, any right to require a proceeding first against the Company, protest, notice and all demands whatsoever.
	(d)		This Subsidiary Guarantee shall not be discharged except by complete performance of the obligations contained in the Notes and the Indenture.
	(e)		If any Holder or the Trustee is required by any court or otherwise to return to the Company, the Subsidiary Guarantors, or any custodian, Trustee, liquidator or other similar official acting in relation to either the Company or the Subsidiary Guarantors, any amount paid by either to the Trustee or such Holder, this Subsidiary Guarantee, to the extent theretofore discharged, shall be reinstated in full force and effect.
	(f)		The Guaranteeing Subsidiaries shall not be entitled to any right of subrogation in relation to the Holders in respect of any obligations guaranteed hereby until payment in full of all obligations guaranteed hereby.
	(g)		As between the Subsidiary Guarantors, on the one hand, and the Holders and the Trustee, on the other hand, (x) the maturity of the obligations guaranteed hereby may be accelerated as provided in Article 6 of the Indenture for the purposes of this Subsidiary Guarantee, notwithstanding any stay, injunction or other prohibition preventing such acceleration in respect of the obligations guaranteed

			hereby, and (y) in the event of any declaration of acceleration of such obligations as provided in Article 6 of the Indenture, such obligations (whether or not due and payable) shall forthwith become due and payable by the Subsidiary Guarantors for the purpose of this Subsidiary Guarantee.
	(h)		The Subsidiary Guarantors shall have the right to seek contribution from any non-paying Subsidiary Guarantor so long as the exercise of such right does not impair the rights of the Holders under the Subsidiary Guarantee.
	(i)		Pursuant to Section 10.04 of the Indenture, after giving effect to any maximum amount and any other contingent and fixed liabilities that are relevant under any applicable Bankruptcy or fraudulent conveyance laws, and after giving effect to any collections from, rights to receive contribution from or payments made by or on behalf of any other Subsidiary Guarantor in respect of the obligations of such other Subsidiary Guarantor under Article 10 of the Indenture shall result in the obligations of such Subsidiary Guarantor under its Subsidiary Guarantee not constituting a fraudulent transfer or conveyance.

     3. Execution and Delivery. Each of the Guaranteeing Subsidiaries agrees that the Subsidiary Guarantees shall remain in full force and effect notwithstanding any failure to endorse on each Note a notation of such Subsidiary Guarantee.

     4. Guaranteeing Subsidiary May Consolidate, Etc. on Certain Terms.

(a)

The Guaranteeing Subsidiaries may not consolidate with or merge with or into (whether or not such Senior Subordinated Note Guarantor is the surviving Person) another corporation, Person or entity whether or not affiliated with such Subsidiary Guarantor unless:

	(i)		subject to Section 10.04 of the Indenture, the Person formed by or surviving any such consolidation or merger (if other than a Subsidiary Guarantor or the Company) unconditionally assumes all the obligations of such Subsidiary Guarantor, pursuant to a supplemental Indenture in form and substance reasonably satisfactory to the Trustee, under the Notes, the Indenture and the Subsidiary Guarantee on the terms set forth herein or therein; and
	(ii)		immediately after giving effect to such transaction, no Default or Event of Default exists.

(b)

In case of any such consolidation, merger, sale or conveyance and upon the assumption by the successor corporation, by supplemental Indenture, executed and delivered to the Trustee and satisfactory in form to the Trustee, of the Subsidiary Guarantee endorsed upon the Notes and the due and punctual performance of all of the covenants and conditions of the Indenture to be performed by the Subsidiary Guarantor, such successor corporation shall succeed to and be substituted for the Subsidiary Guarantor with the same effect as if it had been named herein as a Subsidiary Guarantor. Such successor corporation thereupon may cause to be signed any or all of the Subsidiary Guarantees to be endorsed upon all of the Notes issuable hereunder which theretofore shall not have been signed by the Company and delivered to the Trustee. All the Subsidiary Guarantees so issued shall in all respects have the same legal rank and benefit under the Indenture as the Subsidiary Guarantees

			theretofore and thereafter issued in accordance with the terms of the Indenture as though all of such Subsidiary Guarantees had been issued at the date of the execution hereof.
	(c)		Except as set forth in Articles 4 and 5 of the Indenture, and notwithstanding clauses (a) and (b) above, nothing contained in the Indenture or in any of the Notes shall prevent any consolidation or merger of a Subsidiary Guarantor with or into the Company or another Subsidiary Guarantor, or shall prevent any sale or conveyance of the property of a Subsidiary Guarantor as an entirety or substantially as an entirety to the Company or another Subsidiary Guarantor.

     5. Releases.

	(a)		In the event of a sale or other disposition of all of the assets of any Subsidiary Guarantor, by way of merger, consolidation or otherwise, or a sale or other disposition of all to the capital stock of any Subsidiary Guarantor, then such Subsidiary Guarantor (in the event of a sale or other disposition, by way of merger, consolidation or otherwise, of all of the capital stock of such Subsidiary Guarantor) or the corporation acquiring the property (in the event of a sale or other disposition of all or substantially all of the assets of such Subsidiary Guarantor) will be released and relieved of any obligations under its Subsidiary Guarantee; provided that the Net Proceeds of such sale or other disposition are applied in accordance with the applicable provisions of the Indenture, including without limitation Section 4.10 of the Indenture. Upon delivery by the Company to the Trustee of an Officer’s Certificate and an Opinion of Counsel to the effect that such sale or other disposition was made by the Company in accordance with the provisions of the Indenture, including without limitation Section 4.10 of the Indenture, the Trustee shall execute any documents reasonably required in order to evidence the release of any Subsidiary Guarantor from its obligations under its Subsidiary Guarantee.
	(b)		Any Subsidiary Guarantor not released from its obligations under its Subsidiary Guarantee shall remain liable for the full amount of principal of and interest on the Notes and for the other obligations of any Subsidiary Guarantor under the Indenture as provided in Article 10 of the Indenture.

     6. No Recourse Against Others. No past, present or future director, officer, employee, incorporator, stockholder or agent of the Guaranteeing Subsidiaries, as such, shall have any liability for any obligations of the Company or any of the Guaranteeing Subsidiaries under the Notes, any Subsidiary Guarantees, the Indenture or this Supplemental Indenture or for any claim based on, in respect of, or by reason of, such obligations or their creation. Each Holder of the Notes by accepting a Note waives and releases all such liability. The waiver and release are part of the consideration for issuance of the Notes. Such waiver may not be effective to waive liabilities under the federal securities laws and it is the view of the Commission that such a waiver is against public policy.

     7. NEW YORK LAW TO GOVERN. THE LAW OF THE STATE OF NEW YORK SHALL GOVERN AND BE USED TO CONSTRUE THIS SUPPLEMENTAL INDENTURE.

     8. Counterparts. The parties may sign any number of copies of this Supplemental Indenture. Each signed copy shall be an original, but all of them together represent the same agreement.

     9. Effect of Headings. The Section headings herein are for convenience only and shall not affect the construction hereof.

     10. The Trustee. The Trustee shall not be responsible in any manner whatsoever for or in respect of the validity or sufficiency of this Supplemental Indenture or for or in respect of the recitals contained herein, all of which recitals are made solely by the Guaranteeing Subsidiaries and the Company.

     IN WITNESS WHEREOF, the parties hereto have caused this Supplemental Indenture to be executed by their respective officers thereunto duly authorized, as of the date first written above.

PEABODY ENERGY CORPORATION						US BANK NATIONAL ASSOCIATION
(“COMPANY”)						(“TRUSTEE”)
By:		/s/ Walter L. Hawkins Jr.				By:		/s/ Philip G. Kane, Jr.
Name: Walter L. Hawkins, Jr.						Name: Philip G. Kane, Jr.
Title: Vice President & Treasurer						Title: Vice President

		Existing Subsidiary Guarantors:
		American Land Development, LLC
		American Land Holdings of Illinois, LLC
		American Land Holdings of Indiana, LLC
		American Land Holdings of Kentucky, LLC
		American Land Holdings of West Viginia, LLC
		f/k/a Appalachian Basin Oil & Gas, LLC
		Arclar Company, LLC
		Arid Operations Inc.
		Big Ridge, Inc.
		Big Sky Coal Company
		Black Beauty Coal Company, LLC
		Black Hills Mining Company, LLC
		BTU Empire Corporation
		BTU Western Resources, Inc.
		Caballo Coal Company
		Caseyville Dock Company, LLC
		Central States Coal Reserves of Illinois, LLC
		Central States Coal Reserves of Indiana, LLC
		COALSALES, LLC
		COALSALES II, LLC
		COALTRADE International, LLC
		COALTRADE, LLC
		Coal Reserves Holding Limited Liability Company No. 1
		Colorado Coal Resources, LLC
		Colorado Yampa Coal Company
		Cottonwood Land Company
		Coulterville Coal Company, LLC
		Cyprus Creek Land Company
		Cyprus Creek Land Resources, LLC
		Dyson Creek Coal Company, LLC
		Dyson Creek Mining Company, LLC
		El Segundo Coal Company, LLC
		El Segundo Employment Company, LLC
		f/k/a El Segundo Coal Resources, LLC
		Falcon Coal Company, LLC
		Gallo Finance Company
		Gold Fields Chile, LLC
		Gold Fields Mining, LLC
		Gold Fields Ortiz, LLC
		Hayden Gulch Terminal, Inc.
		Highwall Mining Services Company
		HMC Mining, LLC
		Illinois Basin Oil & Gas, LLC
		Independence Material Handling, LLC
		James River Coal Terminal, LLC
		Juniper Coal Company
		Kayenta Mobile Home Park, Inc.
		Lively Grove Energy Partners, LLC
		Marigold Electricity, LLC
		Marigold Energy, LLC
		Midco Supply and Equipment Corporation

		Midwest Coal Acquisition Corp.
		Midwest Coal Reserves of Illinois, LLC
		Midwest Coal Reserves of Indiana, LLC
		Midwest Coal Resources, LLC
		Mustang Energy Company, L.L.C.
		New Mexico Coal Resources, LLC
		Peabody America, Inc.
		Peabody Archveyor, L.L.C.
		Peabody Cardinal Gasification, LLC
		Peabody Development Company, LLC
		Peabody Electricity, LLC
		Peabody Energy Generation Holding Company
		Peabody Energy Investments, Inc.
		Peabody Energy Solutions, Inc.
		Peabody Holding Company, LLC,
		Peabody International Services, Inc.
		Peabody Investments Corp.
		Peabody Natural Gas, LLC
		Peabody Natural Resources Company
		Peabody Powertree Investments, LLC
		Peabody Recreational Lands, L.L.C.
		Peabody Southwest, LLC
		f/k/a Rockies Natural Gas, LLC
		Peabody Southwestern Coal Company
		Peabody Terminals, LLC
		Peabody Venezuela Coal Corp.
		Peabody Venture Fund, LLC
		Peabody-Waterside Development, L.L.C.
		Peabody Western Coal Company
		PEC Equipment Company, LLC
		Point Pleasant Dock Company, LLC
		Pond River Land Company
		Porcupine Production, LLC
		Porcupine Transportation, LLC
		Powder River Coal, LLC
		Powder River Resources, LLC
		Randolph Land Resources, LLC
		Randolph Land Holding Company, LLC
		Riverview Terminal Company
		School Creek Coal Company, LLC
		School Creek Coal Resources, LLC
		Seneca Coal Company
		Shoshone Coal Corporation
		Star Lake Energy Company, L.L.C.
		Sugar Camp Properties, LLC
		Thoroughbred Generating Company, LLC
		Thoroughbred Mining Company, L.L.C.
		Twentymile Coal Company
		West Roundup Resources, Inc.
		Williams Fork Coal Company, LLC
		Williams Fork Coal Resources, LLC
		Wyoming Natural Gas, LLC

SCHEDULE I

New Guaranteeing Subsidiaries

Century Mineral Resources, Inc., an Illinois corporation
Hillside Recreational Lands, LLC, a Delaware limited liability company
Illinois Land Holdings, LLC, an Illinois limited liability company
Kentucky Syngas, LLC, a Delaware limited liability company
Peabody Terminal Holding Company, Inc., a Delaware corporation