Gold is formed from a process magmatisme or mineral concentration at the surface. Some precipitate formed due process and hydrothermal solutions metasomatis contacts and often together minerals pyrite and other sulfides, silver-gold telurid, skhelit and tourmaline, whereas the concentration of sediment mechanically produce put (placer). as are generally contained in a hydrothermal zone where hydrothermal zones in general is a volcanic area. Some solutions come from the release of water contained in the magma when the magma rises and cools. Others originated from meteoric water or sea water circulating in the crust. Mineral deposit formed by the heated sea water volcanic activity, and sediment shaped sulfide compound, called volcano genic massive sulfide deposits.
Genesis of gold itself is said that gold comes from a reservoir that is the core of the earth from
which the magmatic water containing sulfide ions, chloride ions, and ion transport tio metal complexes of gold to the surface of the earth. The direction of flow of chemical solution containing gold are generally in line with the volcanic magma channel forming veins of gold. When a solution of gold deposited on the channel that has been frozen magma hydrothermal process, which is heading volcanic activity occurred from contact with meteoric water, hot rocks or magmatic water upward movement in which both carry and dissolve the sulfide-chloride ion complex-tio which causes the deposited gold on earth's surface. When the gold bearing veins become weak, then gold will be separated and then precipitate as eluvial deposits, or transported by water flow and settle in a place as a deposit put (placer deposit), together with sand, or gravel
         Based on these explanations, the analisisadanya gold can be traced from the trail or the general process of hydrothermal circulation in the world called epithermal mine in an area, pyrite (Fe2S) called Fools Gold is also often found along with gold. The content of gold as inclusions also sometimes be found in rocks that contain silver and copper.
Gold deposition may also be formed through a process of weathering of igneous rocks and gold veins that can erode and move the gold minerals into a very fine clay material.If there is no intrusion, there may be gold mineral in limestone that is gold minerals from the weathering of igneous rocks that experienced hydrothermal processes in distant places, but there is likely very small gold content of a large and economically advantageous in the limestone due to the very nature of limestone porous
         Mineral deposits in the volcanogenic massive sulfide ore deposits of igneous origin of the continental crust. Heated seawater reacts with rocks in contact with it, causes changes in mineral composition and the solution. For example, feldspar turned into clay and epidote, pyroxene to chlorite. when the mineral undergoes a transformation, raw (trace) metals such as copper and zinc, contained in the substitution of atoms, is free and concentrated in hydrothermal solutions which are formed slowly. this solution through the cooler rock fracture the next plutons feldsik and crystallized in veins and cavities. In certain conditions the concentration of ore minerals associated with the gangue, can be so massive that replaces the original rock (host rock). But other conditions, ore minerals present in small granules scattered in the host rock.
         The richest placers are not necessarily those occurring close to the source. Much depends on how the placer materials were reworked by natural forces. Streambed placers are the most important kind of deposit for the small-scale operator, but the gravel terraces and benches above the streams and the ancient river channels (often concealed by later deposits) are potential sources of gold. Other types of placers include those in outwash areas of streams where they enter other streams or lakes, those at the foot of mountainous areas or in regions where streams enter into broader valleys, or those along the ocean front where beach deposits may form by the sorting action of waves and tidal currents. In desert areas, placers may be present along arroyos or gulches, or in outwash fans or cones below narrow canyons. Because gold is relatively heavy, it tends to be found close to bedrock, unless intercepted by layers of clay or compacted silts, and it often works its way into cracks in the bedrock itself. Where the surface of the bedrock is highly irregular, the distribution of gold will be spotty, but a natural riffle like surface favors accumulation. Gold will collect at the head or foot of a stream bar or on curves of streams where the current is slowed or where the stream gradient is reduced. Pockets behind boulders or other obstructions and even moss-covered sections of banks can be places of deposition. Best results usually come from materials taken just above bedrock. The black sands that accumulate with gold are an excellent indicator of where to look.