In addition to the provision of law now in force in respect to the abandonment of mining claims, they may be abandoned in the following manner: the owner or owners of any mining claim, wishing to abandon the same, may sign and acknowledge in the same manner provided by law for the acknowledgment of deeds, and file for record in the office of the county clerk, a certificate describing the same, stating when and by whom located, the name of the claim, the book and page where the notice of location of such claim is recorded; that he or they give up and abandon such claim, and that the same is open and subject to relocation. Upon the filing of such certificate, the mining claim therein described shall be considered abandoned and open to relocation as if the same had never been located, and the owner or owners thereof forever estopped from claiming any right or interest therein under the location mentioned in said certificate; provided, that this provision for abandonment shall not apply to any claim or location upon which any mortgage, lien or other encumbrance exists.