Abstarct: Angoranchay placer gold deposit with an area of about 0.36 km2, is situated in Zanjan province, 10 km southeast of Mahneshan, and at the junction of Angoranchay and Qezel Ozan river. This deposit is located in the northern part of Sanandaj-Sirjan zone, which is one of the most significant gold-bearing mextallogenic belts in Iran. The upstream rock units of the Angoranchay placer include the Late Precambrian rock assemblages with gneiss, amphibolite, micachist, marble and granite lithology, Oligocene lower red formation with conglomerate and thick bedded sandstone, Oligo-Miocene sedimentary-pyroclastic sequences with limestone, marl, conglomeratic limestone, rhyolitic and andesitic tuff and lava flows. Weathering and erosion release gold and the other heavy minerals from source rocks in the upstream and concentrate these minerals in the Angoranchay placer. The survey study results show that Au grade in -80 mesh fration of sediments is higher than other size fractions. The average and maximum gold grade in -80 mesh fration of sediments is 190 and 3570 ppb, respectively, which is 63 and 1190 times richer than the crustal abundance of Au (about 3 ppb). magnetite, ilmenite, hematite, oligist, spinel, garnet, pyroxene, amphibole, epidote, chlorite, biotite, apatite, zircon, rutile, anatase, sphene, leucoxene, pyrite, galena, sphalerite, cerussite, smithsonite, native lead, chalcopyrite, malachite, corundum, cinnabar, barite, fluorite, scheelite, realgar, orpiment, and stibnite.The minimum, average, and maximum of native gold values are 47, 274, and 991 ppb, respectively. The mean length and width of gold grains are 393 and 239 micrones baxsed on microscopic observations, and 331 and 190 micrones baxsed on SEM technique. The morphological study of 260 gold particles shows that these particles have lumpy (190 particles), platy (50 particles), bar (10 particles), fibrous- lamelar (5 particles), and film (5 particles) shapes. Native gold grains are rounded (60% grains), semi-rounded (25% grains), semi-angular (10% grains), and well-rounded (5% grains), indicating that the gold-bearing source rocks are at different distances from the Angoranchay placer. The study of gold grains chemistry by EPMA shows that the Au, Ag, and Cu form the major composition of gold grains. The average values of Au in the rim and core of gold grains are 91.93 and 88.79%, Ag 2.31 and 5.74%, and Cu 0.01 and 0.03%, respectively. The Au grade in the rim of grains is higher than their core, which indicates the dissolution of Ag during the erosion and weathering of gold grains. The fineness index of gold particles varies from 900 to 1000 and indicates the high purity of gold particles. Comparison of the chemical composition of native gold grains from the Angoranchay placer with those of various gold deposits display that their similarity and affinity with epithermal gold deposits. The reservoir of native gold (> 60 µ in size) in the Angoranchay placer to depth of 5 meters is estimated about 1233 kg.