delivered the opinion of the court.
We think the learned judge who delivered the opinion of the court of appeals was in error in assuming that the record in the case presented a question as to the right of an alien to acquire by location a transferable interest in a mining claim. That question, under the facts presented, could not be raised by the plaintiff. While it is true that the mineral lands of the government are open to location and purchase only by a citizen of the United States, or one who has declared his intention to become such, and the fact of alienage, if raised at the proper time by any one adversely interested, will defeat the acquirement of title thereto, yet the qualifications of an applicant for a patent, as well as the fact of discovery and the compliance on his part with other requirements made essential by the act of congress to entitle him to purchase the mineral land of the government, being cognizable by the officers of the land department, when in the exercise of their jurisdiction they approve the application and allow an entry, the fact of citizenship, as well as all other questions of fact, is presumed to have been established, and is not open to review by the courts at the instance of third parties.
As was said by Justice Field, speaking for the court in Steel v. Smelting Co., 106 U. S. 447:
“We have so often had occasion to speak of the land department, the object of its creation, and the powers it possesses in the alienation by patent of portions of the public lands, that it creates an unpleasant surprise to. find that counsel, in discussing the effect to be given to the action of that department, overlook our decisions on the subject. That department, as we have repeatedly said, was established to supervise the various proceedings whereby a conveyance of the title from the United States to portions of the public domain is obtained, and to see that the require*263ments of different acts of congress are fully complied with. Necessarily, therefore, it must consider and pass upon the qualifications of the applicant, the acts he has performed to secure the title, the nature of the land, and whether it is of the class which is open to sale. Its judgment upon these matters is that of a special tribunal, and is unassailable except by direct proceedings for its annulment or limitation.”
It is now too well settled to admit of discussion, that after the “ grant of title, or the equivalent, is made to an alien, it cannot be attacked by any third party.” Billings v. Aspen M. & S. Co., 52 Fed. Rep. 250; Governeur's Heirs v. Robertson, 11 Wheat. 332; Craig v. Leslie, 3 Wheat. 563.
If the right of a third party to attack the validity of a patent when issued, upon the ground of the alienage of the patentee, was a debatable question, it is clear that the present action was prematurely brought. . At the time of its commencement the proceedings in the land office were yet pending, and that department had exclusive jurisdiction of the matter, and any. attempt on the part of the courts to control its action would be an unwarranted assumption of jurisdiction, under the circumstances. In either view, this action cannot be maintained, and the demurrer should be sustained. -The judgment of the court of appeals must therefore be reversed and the cause remanded, with directions to affirm the judgment of the district court.
Reversed and remanded.