The Occurrence Characteristics of Gold in the Jiaojia Gold Deposit

The Jiaojia Gold Mine is one of the most important gold deposits in the Laizhou-Zhaoyuan gold mine, in which gold occurrence is complex. Previous research has focused on mineral types and shapes, gold-bearing ore species and relationship between minerals. However, studies of detailed gold mineralogy, occurrence characteristics, and fineness of different gold grain have been largely overlooked. The samples collected from the Jiaojia Gold Mine were comprehensively studied using Advanced Polarized Light Reflective Dual Microscope, Stereoscopic Microscope, Scanning Electron Microscopy, Energy Spectrometer and X-ray Diffractometer. The results show as following: main gold bearing minerals are sulfide and gangue, sulfide was mainly pyrite and chalcopyrite, gangue was mainly quartz and feldspar. The occurrence types of gold included 64.82% of intercrystalline gold, 19.29% of inclusion gold and 15.89% of fissure gold. Gold size was larger in pyrite and chalcopyrite than in gangue minerals. Meanwhile, the majority of gold was distributed as groups in sulfide minerals and isolation in gangue minerals. The gold shapes were mainly spherical, triangular and rectangular. Gold species were abundant, such as natural gold, electrum, and natural silver and natural silver including iron, and less as auricupride, acanthite, gold and silver telluride. The sizes of gold have a wide range, as large grains are up to 90-110 μm and small grains are 2-3 μm. The fineness of large gold particles was low and the main ingredient was electrum, whose main ingredient was natural gold in small particles.