Gold nuggets are usually marked 20K to 22K pure, containing 83% to 92% gold. These places might be just a few hundred years old or be millions of years old. Gold nuggets may come from old placers, known as paleoplacers, being eroded.Gold nuggets form when groundwater rich in gold deposits gets precipitated in soils and gravels.Interestingly, often gold particles get bigger as nuggets for a few miles downstream of the primary source of gold. Shearing and hammering create small gold nuggets and then they are bound together by squeezing, hammering, and shearing in moving gravels. During weathering and transportation, smaller gold crystals (or particles) may stick together by pressure and end up in a slope or stream bed. Another theory suggests the gold nuggets form because gold is sticky, bendable, and malleable.Later, the formed tiny gold molecules join together and form crystalline nuggets. Theory of CrystallizationĪccording to this, nuggets are formed deep under the earth’s surface at extreme temperature and pressure. A bacterium called Cupriavidus metallidurans creates such nuggets.Īccording to a 2007 report, bacteria and archaea are found to be the driving force of solubilizing and precipitating gold. Nuggets are said to be formed after bacteria dissolve gold into nanoparticles which move through rocks and form clumps or aggregates. The colloidal grains then accumulate until they become gold nuggets. A gold colloid is created through soluble gold complexes saturated with hydrothermal fluids which then allowed gold particles to be moved into the suspension fluid. Theory of PrecipitationĪccording to this theory, nuggets are formed near the surface as gold particles precipitated from solutions arising from weathering of old gold deposits. The famed Victorian nuggets of Australia were believed to be formed by erosion because of the abundance of quartz in them. Theory of ErosionĮarlier it was believed that gold nuggets were formed in gold-rich reefs as they eroded over time. Some theories regarding nugget formation: 1. Over time, they weathered and ended up in water bodies due to gravity. Most of the gold nuggets found so far were formed as clusters of gold from very hot water in cracks and fissures in hard-rocks, often with quartz. The origin of nuggets is a matter of debate.
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