Section 50
SEC. 50. Proof of citizenship and of age under the clauses of this Act relating to location and lease of mineral lands may consist, in the case of an individual, of his own affidavit; in the case of an association of persons unincorporated, of the affidavit of their authorized agent made on his own knowledge; and in the case of a corporation organized under the laws of the Philippines, by the filing of a certified copy of its charter or certificate of incorporation, accompanied by the affidavit of any duly authorized representative of the corporation cognizant of the facts, certifying that at least sixty per centum of its capital is owned and held by citizens of the Philippines.