delivered the opinion of the court.
This is an appeal from a judgment rendered and entered after an order sustaining defendants ’ demurrer to the complaint *101and denying plaintiff an injunction. The facts alleged as grounds for relief are these:
On August 27, 1908, the plaintiff conveyed to one Magnus Lindstrand section 35, township 8 N., range 25 E., in Mussel-shell county, reserving ‘1 all coal and iron upon or in said land, and also the use of such surface ground as may be necessary for the exploring for and mining or otherwise extracting and carrying away the same.” In the year 1913 the assessor of Musselshell county assessed the reservation so made, for the purpose of taxation, at a valuation of $18 per acre, making a total valuation of the reservation for the entire section of $11,520. The amount of tax levied for that year was $276.48. The plaintiff having failed to make payment, the reservation was sold by the treasurer and bought in for the county in January, 1914. For each of the years 1914, 1915 and 1916, the reservation was again assessed at the same valuation. Taxes were levied as in 1913, but were not paid. The land contains coal. This, however, has never been explored or developed, and, it is alleged, the quantity, quality and value of it are speculative and matters of opinion. No use of the surface of the land for the purposes stated in the reservation has ever been made by the plaintiff. It is alleged: “That the assessor in making said assessment in the year 1913 and said other assessments took into consideration and fixed and determined the valuation of such reservation on the basis of the quantity and quality of the coal in said land and the value thereof according to his opinion, and did value and assess said coal, and said taxes for which said property was sold were imposed and levied upon said coal and other property so reserved. ’ ’ The defendant treasurer of the county threatens to make and deliver to the county a tax deed conveying to it the reservation including the coal. To prevent this action on his part, and thus the casting of a cloud upon plaintiff’s title, this action was brought.
The theory upon which the action proceeds is that the tax is wholly illegal, and hence that under the decision in Barnard Realty Co. v. City of Butte, 50 Mont. 159, 145 Pac. 946, the *102remedy by injunction is available, without allegation and proof of the fact that an unsuccessful application has been made for relief to the board of county commissioners while sitting as a board of equalization. The inquiry presented by the appeal’ therefore is whether the reservation in the deed which includes only coal in an undeveloped condition and not yet transformed into a mine, is a proper subject for taxation. The same inquiry was before this court in the case of Northern Pac. Ry. Co. v. Mjelde, 48 Mont. 287, 137 Pac. 386. That this is so is shown by the statement in the opinion in that case of the question to be determined as follows: “We are called upon to determine whether that which the company reserved to itself in each of these parcels of land, constitutes property which is subject to taxation.” The reservation to which this reference was made included “all mineral of any nature whatsoever” as well as coal and iron; but this fact does not distinguish it from this ease. Neither is it distinguishable from this case by the fact that there were therein considered two reservations, one of which was in land assumed to contain coal, whereas it was not known what the contents of the other were. It was then definitely determined that such a reservation is an interest in real estate, and is subject to taxation. It was also determined that the reservation is not a mine nor a mining claim, within the language employed in section 3 of Article XII of the Constitution. It was held further that the expression “mining claim,” as used therein, means a tract of land to which the right of possession or title has been acquired under the laws of Congress providing for the sale of mineral lands as such, including coal lands, and that the term “mine” means a mining property so developed as to yield, or to be capable of yielding, a profit. The term “mine” was thus construed as broad enough to include within its scope and meaning any developed and producing body of ore, without reference to how the title to the land in which it is found has been acquired. The language employed in this connection is the following: “The character of legislation, under which title or right of possession is acquired, is not a controlling factor at *103all. A mine upon a patented homestead is not less a mine because title from the government was acquired under laws «providing for the disposition of agricultural lands only; and an undeveloped body of ore is not a mine, though title to it was secured under the mineral laws, but it is merely a part of the real estate itself. In providing a fundamental law for the new state, the framers of our Constitution spoke in comprehensive terms; but we decline to believe that they used the word ‘mine’ in section 3 in a sense which would include hidden, unknown, or undeveloped deposits of ore or coal. In that section they spoke with reference to revenue and referred to something which would or might produce revenue in its present state of development.” If this is accepted as the correct meaning of the term, all mines as distinguished from mining claims, wherever they are found, if developed, are put in the same class for the purpose of taxation. Nevertheless we held, not directly but impliedly, that, until developed, ore bodies underlying land obtained from the federal government by grant or conveyance under other than the laws relating to the disposition of mineral lands, are an element of value of the land, and are to be taxed as a part of it. The final conclusion was stated as follows: “In the absence of any allegation bringing either of these rights [the two reservations under consideration] within the definition of a mine, or disclosing that they are, or either of them is, valueless, the complaint fails to state a cause of action. If this conclusion in its ultimate analysis involves a classification of property, which will result in denying to any person within this jurisdiction the equal protection of the laws — and we do not think that it does — the responsibility must rest upon the framers of our Constitution, who, in their zeal to promote the mining industry, arbitrarily gave to mines and mining claims a status before the law not enjoyed by other species of property.”
That decision is conclusive of this case, if based upon a correct conception of the purpose had in view by the constitutional convention. Upon a more mature consideration of the subject, however, aided by the light shed upon it by a study of the de*104bates which occurred at the time of the formulation of the Article relating to revenue (Article XII), we are convinced that our conclusion is not entirely in accord with the aim of the convention. As expressive of the purpose that all property shovdd bear its just proportion of the burden of supporting and maintaining the government, the convention adopted section 1. Under this it became the duty of the legislature to provide for a uniform rate of assessment and taxation, upon a just valuation of all property, except as otherwise provided in other sections of the Article. By section 16 it was made the duty of the legislature to provide generally the manner of assessment, except as otherwise provided, there being added a specific provision as to who should assess railroad property. In section 17 the convention defined the meaning of the term “property.” In section 2 it provided for exemptions, enumerating what property was to be absolutely exempt, and what the legislature might in its discretion exempt. The purpose of section 3 was to provide a special method for the assessment and taxation of mining property. The making of the special provision on the subject shows conclusively that the convention was of the opinion that this species of property, though falling generally within the definition of “property” as made in section 17, could not be justly dealt with by the method provided for other real’property, and therefore must be valued and taxed by a method whieh would accomplish this desired result. The theory adopted was that it should be regarded as of a mixed quality — real as to the surface value, and personal as to the subsurface contents of it. This is apparent from a reading of it: “All mines and mining claims, both placer and rock in place, containing or bearing gold, silver, copper, lead, coal, or other valuable mineral deposits, after purchase thereof from the United States, shall be taxed at the price paid the United States therefor, unless the surface ground, or some part thereof, of such mine or claim, is used for other than mining purposes, and has a separate and independent value for such other purposes, in which case said surface ground, or any part thereof, so used for other than mining purposes, shall be *105taxed at its value for such other purpose, as provided by law; and all machinery used in mining, and all property and surface improvements upon or appurtenant to mines and mining claims which have a value separate and independent of such mines or mining claims,' and the annual net proceeds of all mines and mining claims shall be taxed as provided by law.” In order that no value should escape from taxation, the surface value was arbitrarily fixed at the price paid for it to the government; the convention presuming, of course, that ordinarily mining property would have no value for any purpose other than for mining. In other words, in their estimation it would have no value except, when it would be in condition to produce profit. That such other value as it might derive from its use for residential, manufacturing and agricultural purposes, it was determined must be ascertained as if it were real estate, and added to the purchase price. The machinery and other improvements put upon the surface and having an independent value, it was determined should be valued as improvements upon other property. To this extent the valuation and assessment were to be ascertained under the provisions of law applicable to other real property. As to the subsurface contents, the theory was adopted that they should be regarded as having no taxable value other than so far as they might add to the resources of the owner by the yielding of a profit. Hence the last clause was added which in effect made an exemption of the contents from taxation so long as they should not prove a source of profit by being extracted and converted into personal property. This theory necessitated the devising of a method of ascertaining the net profits, and a mode by which their taxable value might be ascertained, a levy thereon made and the collection of it enforced, at a rate uniform with that laid upon all personal property. That the convention determined that such property, when not a source of profit to the owner of the surface, should not be subject to taxation is made clear as well by the previous legislation on the subject as by the special scheme devised in section 3. (Northern Pac. Ry. Co. v. Mjelde, supra.) In announcing our conclu*106sion in Ms case we were of the opinion that in adopting section 3, the convention intended to be understood as confining its application exclusively to mines purchased from the United States. If, however, the definition of the term “mine,” as adopted in the Mjelde Case, is correct — and we think it is — it is broad enough to include mines wherever found.
The debates had in the convention are not easily accessible be-[1, 2] cause they have not yet been published. Previous to the adoption of section 3, however, there was much diversity of opinion among the members. Some of them advocated the elimination of any special provision on the subject of mines and mining claims; these entertaining the opinion that mineral deposits should be taken into the estimate as an element of value, whether they had been developed or not. The adoption of this plan would have put all lands into the same class. Others, and by far the larger number, advocated the adoption of section 3, upon the theory that however rich a deposit might apparently be or was supposed to be, the real value was at best a matter of speculation ; that it was varying and uncertain; that it might be of great apparent value to-day and by to-morrow of no apparent value — ■ this because of changed conditions found in the earth in the process of development, and because in its undeveloped state no intelligent estimate of its value could be made by the assessing officer. While the discussion had special reference to land acquired under the laws relating to mineral lands, it disclosed a purpose to devise a method by which all property could be made to bear its just burden under an ascertainable value, as well as a definite purpose to avoid leaving the ascertainment of the value of any of it to speculation which would vary in result as widely as the individual opinions or judgments of different assessors, and thus result in valuations in no sense uniform as to that particular class of property. The language of the section is not expressed in the most apt and appropriate terms; but we are of the opinion that the expression “all mines,” as used in the last clause of it, was intended to apply to all mineral deposits, and to put them in the category of personal property; the margin *107over and above the cost of extraction only to be taxed at a value to be ascertained by visual inspection or mathematical calculation. In any event, it is broad enough to include all, both those found in lands purchased from the United States under the mining laws, and those obtained by grant or purchase under other laws. Indeed, there is no reason to suppose the convention, in devising a method for the taxation of mineral deposits, gave careful attention exclusively to mines and mining claims purchased as such, omitting all consideration of those acquired by other modes, though many members must have had knowledge of the existence or possible discovery of the latter. We must conclude that the members were fully informed that the grant of lands now held by the plaintiff included coal and iron. We must conclude, also, that they knew that lands acquired by settlers under the homestead and other laws relating to the disposition of agricultural lands were possibly underlaid with mineral deposits. Presuming that they had this knowledge, it would be doing violence to their intelligence to conclude that they arbitrarily and without reason left such deposits to be valued and taxed according to the varying opinions of different assessors, without considering whether they could be made a source of actual profit. It is more reasonable to suppose that by the use of the general language employed in the last clause, they intended to include all mineral deposits, and to declare that their taxable value should be their productive value after development. It is more reasonable also to conclude that they intended to classify mines as such, rather than that they intended to classify them with reference to the law by which title was acquired, and thus leave themselves open to the imputation that they made an arbitrary classification. This would necessarily have been the result, for it would follow that coal lands acquired under the law providing for their disposition as such would be taxable under section 3, supra, whereas a homestead adjoining would be taxed upon its undeveloped coal as an element of value.
So far as these views are in conflict with the final conclusion announced in the Mjelde Case, the latter is to be considered as *108overruled. It does not follow, however, that the reservation in [3] controversy is without any taxable value. The right reserved to the use of the surface is of substantial value and may be availed of at any time. It includes so much of the surface as may be necessary to explore, develop and extract either coal or iron; the extent or duration of the use being limited only by the extent of the deposit. This necessarily detracts from the value of the land to the plaintiff’s grantee, and to this extent it is an interest in the land itself, and is properly the subject of taxation. (Const., Art. XII, see. 17; Rev. Codes, secs. 2498, 2501.)
This brings us to the question: How is its value to be ascer[4] tained? The only answer is that the cash value of the land, omitting the deposit from the estimate, is to be ascertained as if the entire estate or land as vested in the grantee, and an equitable apportionment of this Value made by the assessor between the grantee and the plaintiff.
It is contended by the Attorney General that though the coal [5] deposit was improperly included by the assessor as the principal element in ascertaining the value of the reservation, inasmuch as the surface right was taken into consideration also, the assessment was valid in part, and hence that the complaint does not state a ease for relief by injunction, because it is not alleged therein that the plaintiff applied to the board of county commissioners while sitting as a board of equalization for relief from the illegal portion of it. To support this contention he cites and relies upon the case of Danforth v. Livingston, 23 Mont. 558, 59 Pac. 916. In that case complaint was made of an overvaluation, and it was properly held that in such a case relief by injunction would not be granted, unless the overvaluation was the result of arbitrary action or fraud by the assessor,- and the board had refused relief. That case is not in point here. The question presented here is whether an injunction will be granted to restrain the issuance of a deed to the purchaser at a tax sale, when the tax to enforce the collection of which the sale was made was in part illegal. Where such a tax is wholly illegal, the sale may *109be enjoined. (Barnard Realty Co. v. City of Butte, supra.) The conclusion reached in that case was held permissible under section 2741 of the Revised Codes, which, though prohibiting generally the issuance of an injunction to restrain the collection of a tax, nevertheless permits the issuance (1) when the tax is wholly or in part illegal or unauthorized by law, and (2) when the property is exempt. In the first case, if any part of the tax is illegal, it must appear that this part has been paid. This presumes, of course, that the legal and illegal portions are separable and the legal part is ascertainable. Here the ease is presented of a gross sum, the legal part of which cannot be ascertained and paid. Clearly the plaintiff ought to have paid the part of it due upon the surface right, but since it could not ascertain what amount was apportioned to this part of the reservation, it could not comply with the statute.
We know of no case in which the same question has been examined and determined. We think, however, that under the anomalous situation in which the plaintiff finds itself, it ought not to be denied the relief demanded. Hence we conclude that the district court erred in sustaining the demurrer, and that the judgment should be reversed.
It is proper to say of the Mjelde Case that in determining It this court did so on the theory that undeveloped coal deposits ought to be considered an element in ascertaining the value of the land in which they are found, and that the levy had been properly made. It is also proper to say that in view of the conclusion announced therein, the district judge was fully justified in sustaining the demurrer and denying the injunction.
Mr. Justice Holloway concurs. , Mr. Justice Sanner concurs in the result.