<SEC-DOCUMENT>0000764065-17-000122.txt : 20170627
<SEC-HEADER>0000764065-17-000122.hdr.sgml : 20170627
<ACCEPTANCE-DATETIME>20170627070153
ACCESSION NUMBER:		0000764065-17-000122
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20170626
FILED AS OF DATE:		20170627
DATE AS OF CHANGE:		20170627

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			CLIFFS NATURAL RESOURCES INC.
		CENTRAL INDEX KEY:			0000764065
		STANDARD INDUSTRIAL CLASSIFICATION:	METAL MINING [1000]
		IRS NUMBER:				341464672
		STATE OF INCORPORATION:			OH
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		200 PUBLIC SQUARE
		STREET 2:		STE. 3300
		CITY:			CLEVELAND
		STATE:			OH
		ZIP:			44114-2315
		BUSINESS PHONE:		216-694-5700

	MAIL ADDRESS:	
		STREET 1:		200 PUBLIC SQUARE
		STREET 2:		STE. 3300
		CITY:			CLEVELAND
		STATE:			OH
		ZIP:			44114-2315

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	CLEVELAND CLIFFS INC
		DATE OF NAME CHANGE:	19920703

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			GONCALVES LOURENCO
		CENTRAL INDEX KEY:			0001236128

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-08944
		FILM NUMBER:		17931131
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wf-form4_149856129880014.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2017-06-26</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000764065</issuerCik>
        <issuerName>CLIFFS NATURAL RESOURCES INC.</issuerName>
        <issuerTradingSymbol>CLF</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001236128</rptOwnerCik>
            <rptOwnerName>GONCALVES LOURENCO</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>200 PUBLIC SQUARE</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 3300</rptOwnerStreet2>
            <rptOwnerCity>CLEVELAND</rptOwnerCity>
            <rptOwnerState>OH</rptOwnerState>
            <rptOwnerZipCode>44114-2315</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Chairman, President &amp; CEO</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Shares</value>
            </securityTitle>
            <transactionDate>
                <value>2017-06-26</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>531674</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>3386970</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Reflects the number of restricted share units granted to the Reporting Person on June 26, 2017 from the Cliffs Natural Resources Inc. Amended and Restated 2015 Equity and Incentive Compensation Plan. This grant vests on December 31, 2019.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ James D. Graham by Power of Attorney</signatureName>
        <signatureDate>2017-06-27</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
