Gold was discovered in Lyman, NH in 1864, sparking a minor rush. Several small mines soon opened in the Bath, N.H. area. These small mines supported two milling operations. About $50,000 worth of gold (at period value) was shipped to the Philadelphia National Mint before economic circumstances closed operations in 1878. A much smaller amount of gold was also shipped to the mint from the Diamond Ledge Mine in Ossipee. None of these mines are currently operating.
Gold is found in certain types of rocks, formed by geologic processes. The weathering of New Hampshire’s gold bearing bedrock broke the rock apart naturally. However, gold does not weather, and this allowed the more resistant gold pieces to be washed away by running water. Gold is approximately 19 times heavier than the same volume of water and gets left on the stream bottom with other heavy rock and mineral pieces.
Gold found in stream gravel is known as a placer deposit (pronounced “plasser”). Panning and dredging are methods of separating the heavy gold flakes and nuggets from the stream gravels. Some gold panning and dredging has been done over the last 300 years of New Hampshire’s history, with varying degrees of success.
The Ammonoosuc Mining District is part of a belt that continues out of Vermont, up the Connecticut River, north into Quebec. This belt comprises of bedrock, which holds the highest potential in the state for important discoveries of gold reserves, as well as other metals. This belt is defined by metamorphic rocks, many of which were originally deposited as “volcanics” which could have been, in part, endowed with gold. The most intensive placer-recovery gold activity in recent years has occurred in surficial deposits (soils and stream sediments) within this belt.
Other areas, including the rocks of the White Mountains and similar rocks to the south such as those within the Pawtuckaway Mountains, are also favorable for gold prospecting. The potential also exists for the occurrence of gold along faults, especially those rich in silica minerals.
As with any hobby, talking and working with other enthusiasts will give you a great deal of information on locations and techniques.