Exhibit 4.12

FOURTH SUPPLEMENTAL INDENTURE

Fourth Supplemental Indenture (this “Supplemental Indenture”), dated as of January 29, 2015, among Armstrong Coal Sales, LLC, a Delaware limited liability company (the “Guaranteeing Subsidiary”), a Subsidiary of Armstrong Energy, Inc., a Delaware corporation (the “Company”), the Company, and Wells Fargo Bank, National Association, as trustee under the Indenture referred to below (the “Trustee”).

W I T N E S S E T H

WHEREAS, the Company has heretofore executed and delivered to the Trustee an indenture (as amended, the “Indenture”), dated as of December 21, 2012, providing for the issuance of 11.75% Senior Secured Notes due 2019 (the “Notes”);

WHEREAS, the Indenture provides that under certain circumstances the Guaranteeing Subsidiary shall execute and deliver to the Trustee a supplemental indenture pursuant to which the Guaranteeing Subsidiary shall unconditionally guarantee all of the Company’s Obligations under the Notes and the Indenture on the terms and conditions set forth herein (the “Note 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 Subsidiary, the Company, and the Trustee mutually covenant and agree for the benefit of each other and for the equal and ratable benefit of the Holders of the Notes as follows:

ARTICLE I

DEFINITIONS

Section 1.01. Capitalized Terms. Capitalized terms used herein without definition shall have the meanings assigned to them in the Indenture.

ARTICLE II

GUARANTEES

Section 2.01. The Guarantees. Subject to the provisions of this Article, the Guaranteeing Subsidiary hereby irrevocably and unconditionally guarantees, jointly and severally, on a senior secured basis, the full and punctual payment (whether at maturity, upon any redemption, by declaration or acceleration, or otherwise) of the principal of, premium, if any, and interest on, and all other amounts payable under the Notes, and the full and punctual payment of all other amounts payable by the Company under the Indenture. Upon failure by the Company to pay punctually any such amount, the Guaranteeing Subsidiary shall forthwith pay the amount not so paid at the place and in the manner specified in the Indenture. The Guaranteeing Subsidiary further agrees to pay any and all expenses (including reasonable counsel fees and expenses) incurred by the Trustee or the Agent in enforcing or exercising any rights under this Note Guarantee.

Section 2.02. Guarantee Unconditional. (a) The obligations of the Guaranteeing Subsidiary hereunder are direct, unsubordinated, unconditional and absolute and, without limiting the generality of the foregoing, shall not be released, discharged or otherwise affected by:

(1) any extension, renewal, settlement, compromise, failure to enforce, waiver or release in respect of any obligation of the Company under the Indenture, this Supplemental Indenture or under the Notes, by operation of law or otherwise;

(2) any rescission, waiver or, subject to Section 12.03 of the Indenture, any modification or amendment of or supplement to, the Indenture or the Notes;

(3) the occurrence or notice of any default or event of default under the Indenture or under any other agreement;

(4) any change in the corporate existence, structure or ownership of the Company, or any insolvency, bankruptcy, reorganization or other similar proceeding affecting the Company or their assets or any resulting release or discharge of any obligation of the Company contained under the Indenture or under the Notes;

(5) the existence of any claim, set-off or other rights which the Guaranteeing Subsidiary may have at any time against the Company, the Trustee or any other Person, whether in connection with the Indenture or any unrelated transactions, provided that nothing herein prevents the assertion of any such claim by separate suit or compulsory counterclaim;

(6) any invalidity or unenforceability relating to or against the Company for any reason of the Indenture or any Note, or any provision of applicable law or regulation purporting to prohibit the payment by the Company of the principal of or interest on the Notes or any other amount payable by the Company under the Indenture; or

(7) any other act or omission to act or delay of any kind by the Company, the Trustee or any other Person or any other circumstance whatsoever which might, but for the provisions of this paragraph, constitute a legal or equitable discharge of or defense to such Guaranteeing Subsidiary’s obligations hereunder.

Section 2.03. Discharge; Reinstatement. The Guaranteeing Subsidiary’s obligations hereunder will remain in full force and effect until the principal of, premium, if any, and interest on the Notes and all other amounts payable by the Company under the Indenture have been paid in full. If at any time any payment of the principal of, premium, if any, or interest on any Note or any other amount payable by the Company under the Indenture is rescinded or must be otherwise restored or returned upon the insolvency, bankruptcy or reorganization of the Company or otherwise, the Guaranteeing Subsidiary’s obligations hereunder with respect to such payment will be reinstated as though such payment had been due but not made at such time.

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Section 2.04. Waiver by the Guaranteeing Subsidiary. The Guaranteeing Subsidiary irrevocably waives acceptance hereof, presentment, demand, protest and any notice not provided for under the Indenture or herein, as well as any requirement that at any time any action be taken by any Person against the Company or any other Person.

Section 2.05. Subrogation and Contribution. Upon making any payment with respect to any obligation of the Company under this Article, the Guaranteeing Subsidiary will be subrogated to the rights of the payee against the Company with respect to such obligation, provided that the Guaranteeing Subsidiary may not enforce either any right of subrogation, or any right to receive payment in the nature of contribution, or otherwise, from any other Guarantor (including any Guaranteeing Subsidiary), with respect to such payment so long as any amount payable by the Company hereunder or under the Notes remains unpaid.

Section 2.06. Stay of Acceleration. If acceleration of the time for payment of any amount payable by the Company under the Indenture or the Notes is stayed upon the insolvency, bankruptcy or reorganization of the Company, all such amounts otherwise subject to acceleration under the terms of the Indenture are nonetheless payable by the Guaranteeing Subsidiary hereunder forthwith on demand by the Trustee or the Holders.

Section 2.07. Limitation on Amount of Guarantee. Notwithstanding anything to the contrary in this Article, the Guaranteeing Subsidiary, and by its acceptance of Notes, each Holder hereby confirms that it is the intention of all such parties that the Note Guarantee of such Guaranteeing Subsidiary not constitute a fraudulent conveyance under applicable fraudulent conveyance provisions of the United States Bankruptcy Code or any comparable provision of state law. To effectuate that intention, the Trustee, the Holders and the Guaranteeing Subsidiary hereby irrevocably agree that the obligations of the Guaranteeing Subsidiary under its Note Guarantee are limited to the maximum amount that would not render the Guaranteeing Subsidiary’s obligations subject to avoidance under applicable fraudulent conveyance provisions of the United States Bankruptcy Code or any comparable provision of state law.

Section 2.08. Execution and Delivery of Guaranty. The execution by the Guaranteeing Subsidiary of this Supplemental Indenture evidences the Note Guarantee of the Guaranteeing Subsidiary, whether or not the person signing as an officer of the Guaranteeing Subsidiary still holds that office at the time of authentication of any Note. The delivery of any Note by the Trustee after authentication constitutes due delivery of the Note Guarantee set forth in this Supplemental Indenture on behalf of the Guaranteeing Subsidiary.

ARTICLE III

MISCELLANEOUS

Section 3.01. Incorporators, Stockholders, Officers and Directors of Company Exempt from Individual Liability. No recourse under or upon any obligation, covenant or agreement contained in the Indenture or in this Note Guarantee, or because of any indebtedness evidenced thereby, shall be had against any incorporator, as such or against any past, present or future stockholder, officer or director, as such, of a Company or the Guaranteeing Subsidiary, or of any successor, either directly or through a Company, Guaranteeing Subsidiary or any successor, under any rule of law, statute or constitutional provision or by the enforcement of any assessment

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or by any legal or equitable proceeding or otherwise, all such liability being expressly waived and released by the acceptance of the Notes by the Holders thereof and as part of the consideration for the issue of the Notes.

Section 3.02. Governing Law. The internal law of the State of New York shall govern and be used to construe this Supplemental Indenture, the Indenture and the Notes, without giving effect to applicable principles of conflict of law to the extent that the application of the laws of another jurisdiction would be required thereby.

Section 3.03. 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. The exchange of copies of this Supplemental Indenture and of signature pages by facsimile or portable document format (“PDF”) transmission shall constitute effective execution and delivery of this Supplemental Indenture as to the parties hereto and may be used in lieu of the original Supplemental Indenture for all purposes. Signatures of the parties hereto transmitted by facsimile or PDF shall be deemed to be their original signatures for all purposes.

Section 3.04. Effect of Headings. The Section headings herein are for convenience only and shall not affect the construction hereof.

Section 3.05. The Trustee and Agent. Neither the Trustee nor the Paying Agent shall be responsible in any manner whatsoever for or in respect of the validity, sufficiency or adequacy of this Supplemental Indenture or Note Guarantee or for or in respect of the recitals contained herein, all of which recitals are made solely by the Guaranteeing Subsidiary and the Company. All of the provisions contained in the Indenture in respect of the rights, privileges, immunities, powers, and duties of the Trustee shall be applicable in respect of this Supplemental Indenture as fully and with like force and effect as though fully set forth in full herein. The Company hereby confirms to the Trustee that this Supplemental Indenture has not resulted in a material modification of the Notes for Foreign Accounting Tax Compliance Act (“FATCA”) purposes.

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IN WITNESS WHEREOF, the parties hereto have caused this Supplemental Indenture to be duly executed, all as of the date first above written.

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