((a)) ** General rule** For the purpose of computing the depletion allowance in the case of mines, wells, and other natural deposits, the term “property” means each separate interest owned by the taxpayer in each mineral deposit in each separate tract or parcel of land.

((b)) ** Special rules as to operating mineral interests in oil and gas wells or geothermal deposits** In the case of oil and gas wells or geothermal deposits—

((1)) ** In general** Except as otherwise provided in this subsection—

((A)) all of the taxpayer’s operating mineral interests in a separate tract or parcel of land shall be combined and treated as one property, and

((B)) the taxpayer may not combine an operating mineral interest in one tract or parcel of land with an operating mineral interest in another tract or parcel of land.

((2)) ** Election to treat operating mineral interests as separate properties** If the taxpayer has more than one operating mineral interest in a single tract or parcel of land, he may elect to treat one or more of such operating mineral interests as separate properties. The taxpayer may not have more than one combination of operating mineral interests in a single tract or parcel of land. If the taxpayer makes the election provided in this paragraph with respect to any interest in a tract or parcel of land, each operating mineral interest which is discovered or acquired by the taxpayer in such tract or parcel of land after the taxable year for which the election is made shall be treated—

((A)) if there is no combination of interests in such tract or parcel, as a separate property unless the taxpayer elects to combine it with another interest, or

((B)) if there is a combination of interests in such tract or parcel, as part of such combination unless the taxpayer elects to treat it as a separate property.

((3)) ** Certain unitization or pooling arrangements**

((A)) ** In general** Under regulations prescribed by the Secretary, if one or more of the taxpayer’s operating mineral interests participate, under a voluntary or compulsory unitization or pooling agreement, in a single cooperative or unit plan of operation, then for the period of such participation—

((i)) they shall be treated for all purposes of this subtitle as one property, and

((ii)) the application of paragraphs (1), (2), and (4) in respect of such interests shall be suspended.

((B)) ** Limitation** Subparagraph (A) shall apply to a voluntary agreement only if all the operating mineral interests covered by such agreement—

((i)) are in the same deposit, or are in 2 or more deposits the joint development or production of which is logical from the standpoint of geology, convenience, economy, or conservation, and

((ii)) are in tracts or parcels of land which are contiguous or in close proximity.

((4)) ** Manner, time, and scope of election**

((A)) ** Manner and time** Any election provided in paragraph (2) shall be made for each operating mineral interest, in the manner prescribed by the Secretary by regulations, not later than the time prescribed by law for filing the return (including extensions thereof) for the first taxable year in which any expenditure for development or operation in respect of such operating mineral interest is made by the taxpayer after the acquisition of such interest.

((B)) ** Scope** Any election under paragraph (2) shall be for all purposes of this subtitle and shall be binding on the taxpayer for all subsequent taxable years.

((c)) ** Special rules as to operating mineral interests in mines**

((1)) ** Election to aggregate separate interests** Except in the case of oil and gas wells and geothermal deposits, if a taxpayer owns two or more separate operating mineral interests which constitute part or all of an operating unit, he may elect (for all purposes of this subtitle)—

((A)) to form an aggregation of, and to treat as one property, all such interests owned by him which comprise any one mine or any two or more mines; and

((B)) to treat as a separate property each such interest which is not included within an aggregation referred to in subparagraph (A).

((2)) ** Election to treat a single interest as more than one property** Except in the case of oil and gas wells and geothermal deposits, if a single tract or parcel of land contains a mineral deposit which is being extracted, or will be extracted, by means of two or more mines for which expenditures for development or operation have been made by the taxpayer, then the taxpayer may elect to allocate to such mines, under regulations prescribed by the Secretary, all of the tract or parcel of land and of the mineral deposit contained therein, and to treat as a separate property that portion of the tract or parcel of land and of the mineral deposit so allocated to each mine. A separate property formed pursuant to an election under this paragraph shall be treated as a separate property for all purposes of this subtitle (including this paragraph). A separate property so formed may, under regulations prescribed by the Secretary, be included as a part of an aggregation in accordance with paragraphs (1) and (3). The election provided by this paragraph may not be made with respect to any property which is a part of an aggregation formed by the taxpayer under paragraph (1) except with the consent of the Secretary.

((3)) ** Manner and scope of election** The elections provided by paragraphs (1) and (2) shall be made, in accordance with regulations prescribed by the Secretary, not later than the time prescribed for filing the return (including extensions thereof) for the first taxable year—

((A)) in which, in the case of an election under paragraph (1), any expenditure for development or operation in respect of the separate operating mineral interest is made by the taxpayer after the acquisition of such interest, or

((B)) in which, in the case of an election under paragraph (2), expenditures for development or operation of more than one mine in respect of a property are made by the taxpayer after the acquisition of the property.

((d)) ** Operating mineral interests defined** For purposes of this section, the term “operating mineral interest” includes only an interest in respect of which the costs of production of the mineral are required to be taken into account by the taxpayer for purposes of computing the taxable income limitation provided for in section 613, or would be so required if the mine, well, or other natural deposit were in the production stage.

((e)) ** Special rule as to nonoperating mineral interests**

((1)) ** Aggregation of separate interests** If a taxpayer owns two or more separate nonoperating mineral interests in a single tract or parcel of land or in two or more adjacent tracts or parcels of land, the Secretary shall, on showing by the taxpayer that a principal purpose is not the avoidance of tax, permit the taxpayer to treat (for all purposes of this subtitle) all such mineral interests in each separate kind of mineral deposit as one property. If such permission is granted for any taxable year, the taxpayer shall treat such interests as one property for all subsequent taxable years unless the Secretary consents to a different treatment.

((2)) ** Nonoperating mineral interests defined** For purposes of this subsection, the term “nonoperating mineral interests” includes only interests which are not operating mineral interests.