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

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2008-09-23</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000008328</issuerCik>
        <issuerName>ATLAS MINING CO</issuerName>
        <issuerTradingSymbol>ALMI</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>2008-09-23</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F2"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>1700000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.5</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>13972415</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Note 2.</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2008-09-24</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F3"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>775000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.5</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>13972415</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Note 3.</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F3"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2008-09-24</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F3"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>775000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.5</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>13972415</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Note 3.</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F3"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">IBS Capital LLC is the general partner of The IBS Turnaround (QP) Fund (A Limited Partnership) and The IBS Turnaround Fund (A Limited Partnership).  IBS Capital LLC is the investment adviser of The IBS Opportunity Fund (BVI), Ltd.</footnote>
        <footnote id="F2">The 1,700,000 shares purchased on September 23, 2008 were purchased as follows: (i) 1,019,265 shares were purchased by The IBS Turnaround (QP) Fund (A Limited Partnership) and (ii) 680,735 shares were purchased by the The IBS Turnaround Fund (A Limited Partnership).  After the completion of the transaction, (i) The IBS Turnaround (QP) Fund (A Limited Partnership) held  9,235,203 shares; (ii) The IBS Turnaround Fund (A Limited Partnership) held 3,436,937 shares; and (iii) The IBS Opportunity Fund (BVI), Ltd. held 1,300,275 shares.</footnote>
        <footnote id="F3">The 775,000 shares sold on September 24, 2008, were sold as follows: (i) The IBS Turnaround (QP) Fund (A Limited Partnership) sold 564,805 shares to The IBS Opportunity Fund (BVI), Ltd. and (ii) The IBS Turnaround Fund (A Limited Partnership) sold 210,195 shares to The IBS Opportunity Fund (BVI), Ltd.  After the completion of the transactions, (i) The IBS Turnaround (QP) Fund (A Limited Partnership) holds 8,670,398 shares; (ii) The IBS Turnaround Fund (A Limited Partnership) holds 3,226,742 shares; and (iii) The IBS Opportunity Fund (BVI), Ltd. holds 2,075,275 shares.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>IBS Capital LLC, by David A. Taft, Manager</signatureName>
        <signatureDate>2008-09-25</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>IBS TURNAROUND FUND (QP) (A LTD PARTNERSHIP) By IBS Capital LLC, Its General Partner, David A. Taft, Manager</signatureName>
        <signatureDate>2008-09-25</signatureDate>
    </ownerSignature>
</ownershipDocument>
