Abstract
The Ô Quý Hồ molybdenum deposit is located at the edge of Phan Si Pan Subterrane where the molybdenum mineralization is disseminated or appears as pockets in quartz veins and porphyritic granite. The analyses of fluid inclusions indicate that the ore mineralization occurs in high-moderate temperature (167-400oC), low salt grade (5,2-16,2% NaCl), quite high solution density (0,64-0,86 g/cm3). The S and Pb isotopes show that the genesis of molybdenum ore is related closely to porphyritic granite of 34-40 Ma in age which is distributed largely in the Phan Si Pan Subterrane and characterizes the stockwork molybdenum deposit.