G.R. No. 207942, January 12, 2015YINLU BICOL MINING CORPORATION, Petitioner, v.TRANS-ASIA OIL AND ENERGY DEVELOPMENTCORPORATION, Respondent.D E C I S I O NBERSAMIN, J.:Rights pertaining to mining patents issued pursuant to the Philippine Bill of 1902 and existing prior to November 15, 1935 are vested rights that cannot be impaired.cralawredAntecedentsThis case involves 13 mining claims over the area located in Barrio Larap, Municipality of Jose Panganiban, Camarines Norte, a portion of which was owned and mined by Philippine Iron Mines, Inc. (PIMI), which ceased operations in 1975 due to financial losses. PIMI’s portion (known as the PIMI Larap Mines) was sold in a foreclosure sale to the Manila Banking Corporation (MBC) and Philippine Commercial and Industrial Bank (PCIB, later Banco De Oro, or BDO).1chanRoblesvirtualLawlibraryIn 1976, the Gold Mining Development Project Team, Mining Technology Division, The Mining Group of the Bureau of Mines prepared a so-called Technical Feasibility Study on the Possible Re-Opening of the CPMI Project of PIM (Mining Aspect) and the Exploration Program (Uranium Project)at Larap, Jose Panganiban, Camarines Norte, which discussed in detail, among others, an evaluation of the ore reserve and a plan of operation to restore the mine to normal commercial mining production and budgetary estimate should the Bureau of Mines take over and run the PIMI Larap Mines. The Government then opened the area for exploration. In November 1978, the Benguet Corporation-Getty Oil Consortium began exploration for uranium under an Exploration Permit of the area, but withdrew in 1982 after four years of sustained and earnest exploration.2chanRoblesvirtualLawlibraryTrans-Asia Oil and Energy Development Corporation (Trans-Asia) then explored the area from 1986 onwards. In 1996, it entered into an operating agreement with Philex Mining Corporation over the area, their agreement being duly registered by the Mining Recorder Section of Regional Office No. V of the Department of Environment and Natural Resources (DENR). In 1997, Trans-Asia filed an application for the approval of Mineral Production Sharing Agreement (MPSA)3over the area in that Regional Office of the DENR, through theMines and Geosciences Bureau (MGB), in Daraga, Albay. The application, which was amended in 1999, was granted on July 28, 2007 under MPSA No. 252-2007-V, by which Trans-Asia was given the exclusive right to explore, develop and utilize the mineral deposits in the portion of the mineral lands.4chanRoblesvirtualLawlibraryOn August 31, 2007, Yinlu Bicol Mining Corporation (Yinlu) informed the DENR by letter that it had acquired the mining patents of PIMI from MBC/BDO by way of a deed of absolute sale, stating that the areas covered by its mining patents were within the areas of Trans-Asia’s MPSA. Based on the documents submitted by Yinlu, four of the six transfer certificates of title (TCTs) it held covered four mining claims under Patent Nos.