The northern Murat Dagi region of western Turkey represents the second largest antimony-producing district in Turkey. The antimony ore occurs as stibnite and secondary Sb oxides in hydrothermally altered ultramafic rocks, marbles, and conglomerate. All host rocks were first strongly silicified and open spaces were lined with crystalline quartz prior to mineralization. Mineralization is largely restricted to faults, fractures, and joints and occurs as irregular pockets, rosettes, vein-fillings, and in cavities. Mineralization is of two types; stibnite with pyrite and marcasite as in the Goynuk mine, and stibnite with no other sulfides as in the Derekoy mine. Mercury minerals are absent. Trace amounts of arsenopyrite and sphalerite are present at the Goynuk mine. Gangue minerals observed in both mineralization stages are quartz, chalcedony, opal, calcite, clay minerals, and fuchsite (?). Major secondary antimony minerals are Sb oxides such as valentinite, cervantite, kermesite, and metastibnite.At least a (middle) Miocene age is assigned to the mineralization from observations made at the Goynuk mine at which the lower part of the Miocene basal conglomerate is mineralized. The occurrence of antimony mineralization in Quaternary travertines and denoted Sb levels in hot springs in the area suggests that mineralization can be as young as Recent.The fluid inclusion data as well as the mineralized assemblage supports an epithermal origin, with mineralization at about 165 degrees C. Low salinity (about 3 equiv wt % NaCl) of the hydrothermal solution suggests large-scale contribution by meteoric waters. The fluid inclusion data suggest a shallow depth of mineralization (less than 200 bars) by hydrothermal solutions.