G.R. No. 139548 ; December 22, 2000
MARCOPPER MINING CORPORATION, petitioner, vs. ALBERTO G. BUMOLO, et al., DALTON PACIFIC RESOURCES, INC., OROPHILIPPINES VENTURES INC., and the MINES ADJUDICATION BOARD (MAB), respondents.

FACTS

Marcopper Mining Corporation registered mining claims in Pao, Kasibu, Nueva Vizcaya, from February to October 1982. Private respondents, including Alberto G. Bumolo and others, had registered their own mining claims in the same area earlier, from July 1981 to September 1988, which were later converted into Mineral Production Sharing Agreements (MPSAs). Marcopper entered into Option Agreements with these claimants in March 1982, securing an exclusive right to explore the area for three years. In December 1982 and March 1987, Marcopper filed Prospecting Permit Applications (PPAs) with government agencies, asserting that portions of the area fell within the Magat River Forest Reservation and the Nueva Vizcaya-Quirino Civil Reservation. However, in 1991, Marcopper terminated the Option Agreements, citing that its exploration revealed the area was geologically weak and of limited tonnage, not justifying further investment.
Subsequently, the DENR Regional Executive Director rejected Marcopper’s PPA in July 1991, finding the area was outside any government reservation, conflicted with existing claims, and had been extensively explored earlier. Marcopper’s motion for reconsideration was denied in 1995, with the DENR upholding the prior rights of the existing claim holders. Marcopper appealed to the Mines Adjudication Board (MAB), insisting the area was within the Magat River Forest Reservation. The MAB affirmed the denial of the PPA in June 1998 and gave due course to the respondents’ MPSA applications. Marcopper’s motion for reconsideration was denied, and the MAB formally joined Dalton Pacific Resources, Inc. and Orophilippines Ventures, Inc. as parties, as they had secured exploration rights from the original claimants via a 1992 Memorandum of Agreement.

ISSUE

Whether the Mines Adjudication Board erred in finding that the area subject of Marcopper’s Prospecting Permit Application was outside the Magat River Forest Reservation.

RULING

The Supreme Court denied the petition and affirmed the MAB’s decision. The Court held that the issue raised by Marcopper was factual in nature, concerning the correct geographical classification of the land. Factual findings of quasi-judicial agencies like the MAB, which possess specialized expertise in their domain, are accorded respect and finality if supported by substantial evidence. In this case, the MAB’s conclusion was firmly supported by the DENR’s technical reports, including a July 1991 Memorandum and subsequent sketch plans from the Lands Management Sector, which consistently plotted the area as outside any government reservation.
The Court found no merit in Marcopper’s argument that a typographical error in coordinate data (allegedly “17” degrees instead of “16” degrees) placed the area within the reservation. This unsupported allegation could not overturn the DENR’s official findings. Furthermore, the Court noted the absurdity of Marcopper’s actions: after terminating its Option Agreements because the area was deemed commercially unviable, it later sought a PPA for the same land. This inconsistency bolstered the reasonableness of the DENR’s and MAB’s rejection. The MAB correctly upheld the prior and existing rights of the private respondents, whose claims were perfected earlier and were in the process of conversion to MPSAs in accordance with law. Thus, the petition was denied for lack of justifiable basis.