A gold nugget is a naturally occurring piece of native gold. Watercourses often concentrate the nuggets and they are recovered by placer mining, but they may also be found in residual deposits where the gold-bearing veins or lodes have decayed. Nuggets are also found in the tailings piles of previous mining operations, especially those left by gold mining dredges. They are never pure 24K in composition but rather about 20 to 22K (~about 83% to 92%). Nuggets are also referred to by their "fineness", for example "865 fine" means the nugget is 865 parts per thousand in gold. The common impurities are silver and copper. Nuggets high in silver content are known as "electrum".
The largest gold nugget ever found was the Welcome Stranger, found at Moliagul, Victoria, Australia in 1869 by John Deason and Richard Oates. It weighed gross, over 2,520 troy ounces (78.38 kg) and returned over 2,284 troy ounces (71.04 kg) net. The largest gold nugget still in existence is the Hand of Faith, found in 1980 using a metal detector.
The biggest gold nugget ever found in California weighed 1,593 troy ounces (49.5 kg; 109.2 lb). It was found in August 1869 in Sierra Buttes by five partners — W.A. Farish, A. Wood, J. Winstead, F.N.L. Clevering and Harry Warner.