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A placer claim is a mining claim on gravel or ground from which minerals are extracted using water. [1] In the United States, the valuable mineral in a placer claim is almost always gold , although other nations mine placer deposits of platinum , tin , and diamonds .
When Congress passed the General Mining Act of 1872, the wording was changed to "or other valuable deposits," giving greater scope to the law. The 1872 law was codified as 30 U.S.C. §§ 22-42 [14] The 1872 act also granted extralateral rights to lode claims, and fixed the maximum size of lode claims as 1500 feet (457m) long and 600 feet (183m ...
Placer mining is an important source of gold, and was the main technique used in the early years of many gold rushes, including the California Gold Rush. Types of placer deposits include alluvium, eluvium, beach placers, aeolian placers and paleo-placers. [2] Placer materials must be both dense and resistant to weathering processes. To ...
Placer mining (/ ˈ p l æ s ər /) [1] is the mining of stream bed deposits for minerals. [2] This may be done by open-pit mining or by various surface excavating equipment or tunneling equipment.
Placer mining is a method of extracting gold from alluvial deposits such as sand, gravel, and sediment. [43] [44] These are known as placer deposits which are typically found in riverbeds, stream beds, and floodplains. [45] These deposits typically contain minerals that are resistant to weathering and eroision like gold, platinum, diamonds, and ...
Exploration of orogenic gold began after the year 1840 when the source of nearby placer gold deposits was being investigated, after which large scale mining operations began in the 1990s. [45] The Mother Lode Homestake is located in South Dakota, USA, and is a historic mine which was host to orogenic gold held within a banded iron formation ...
As more miners flooded into the region, placer mining became less profitable and gold more scarce. Remaining pieces of gold were unattainable and embedded deep within the hillsides of the Mother Lode. [9] As a result, many miners took an interest in new techniques and technologies that could be used to obtain the deeper gold fields.
High-grade gold ore from the Harvard Mine, Jamestown, California, a wide quartz-gold vein in California's Mother Lode. Specimen is 3.2 cm (1.3 in) wide. Various theories of ore genesis explain how the various types of mineral deposits form within Earth's crust. Ore-genesis theories vary depending on the mineral or commodity examined.