Abstract: Cosalite crystals are found in small cavities in skarn zones at Uludağ" scheelite deposit associated with pyrite and quartzcrystals. Needle-like prismatic cosaîite crystals usually form parallel aggregates. Unitcell dimensions, space-group, x-ray powderdiffraction pattern and chemical composition have been determined. Native silver is observed under ore microscope and alsorevealed by mieroprobe analysis.