<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2008-05-23</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000008328</issuerCik>
        <issuerName>ATLAS MINING CO</issuerName>
        <issuerTradingSymbol>ALMIE</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001414860</rptOwnerCik>
            <rptOwnerName>IBS CAPITAL LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>ONE INTERNATIONAL PLACE</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 2401</rptOwnerStreet2>
            <rptOwnerCity>BOSTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02110</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001415021</rptOwnerCik>
            <rptOwnerName>IBS TURNAROUND FUND (QP) (A LTD PARTNERSHIP)</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>ONE INTERNATIONAL PLACE</rptOwnerStreet1>
            <rptOwnerStreet2>STE 2410</rptOwnerStreet2>
            <rptOwnerCity>BOSTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02110</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2008-05-23</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>583333</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.6</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>10272415</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Note 1.</value>
                    <footnoteId id="F1"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">IBS Capital LLC is the general partner of (i) The IBS Turnaround (QP) Fund (A Limited Partnership), which holds 6,677,253 shares, and (ii) The IBS Turnaround Fund (A Limited Partnership), which holds 2,294,887 shares.  IBS Capital LLC is the Investment Manager of The IBS Opportunity Fund (BVI), Ltd., which holds 1,300,275 shares.  The 583,333 shares purchased on May 23, 2008 were purchased as follows: (i) 413,262 shares were purchased by The IBS Turnaround (QP) Fund (A Limited Partnership) and (ii) 170,071 shares were purchased by the The IBS Turnaround Fund (A Limited Partnership).</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>IBS Capital LLC, by David A. Taft, Manager</signatureName>
        <signatureDate>2008-05-28</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>IBS TURNAROUND FUND (QP) (A LTD PARTNERSHIP) By IBS Capital LLC, Its General Partner, David A. Taft, Manager</signatureName>
        <signatureDate>2008-05-28</signatureDate>
    </ownerSignature>
</ownershipDocument>
