Results 241 to 250 of about 6,618 (292)
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1987
Placer deposits provided early man with the first samples of gold and thereafter have accounted for a large production of the metal. If we include the Witwatersrand and other quartz-pebble conglomerates as fossil placers or modified placers, the placer type of auriferous deposit has provided more than two thirds of the world’s store of gold, about 80 ×
J. B. Tyrrell +12 more
exaly +2 more sources
Placer deposits provided early man with the first samples of gold and thereafter have accounted for a large production of the metal. If we include the Witwatersrand and other quartz-pebble conglomerates as fossil placers or modified placers, the placer type of auriferous deposit has provided more than two thirds of the world’s store of gold, about 80 ×
J. B. Tyrrell +12 more
exaly +2 more sources
2020
Placer gold deposits are abundant in Mongolia and form through endogenic and exogenic processes. Deposits are classified into four major genetic types: (1) eluvial-weathering zone, (2) deluvial, (3) proluvial, and (4) alluvial. The most economic deposits are often sourced from upper Cretaceous rocks and formed in late Cenozoic alluvial fans (Liskun and
Tankhain Semeihan, Uyanga Bold
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Placer gold deposits are abundant in Mongolia and form through endogenic and exogenic processes. Deposits are classified into four major genetic types: (1) eluvial-weathering zone, (2) deluvial, (3) proluvial, and (4) alluvial. The most economic deposits are often sourced from upper Cretaceous rocks and formed in late Cenozoic alluvial fans (Liskun and
Tankhain Semeihan, Uyanga Bold
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Economic Geology, 2003
Recent fluvial sediments of the Rio Neuquen, Argentina, contain variable amounts of placer gold. In addition to rounded, detrital placer gold, the sediments also contain pristine crystalline gold (type 1 gold), which occurs as overgrowths on detrital placer gold cores. Type 1 gold is locally rimmed by gold with a wormlike or crystalline texture (type 2
A. J. McCready, J. Parnell, L. Castro
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Recent fluvial sediments of the Rio Neuquen, Argentina, contain variable amounts of placer gold. In addition to rounded, detrital placer gold, the sediments also contain pristine crystalline gold (type 1 gold), which occurs as overgrowths on detrital placer gold cores. Type 1 gold is locally rimmed by gold with a wormlike or crystalline texture (type 2
A. J. McCready, J. Parnell, L. Castro
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The in vitro formation of placer gold by bacteria
Geochimica et Cosmochimica Acta, 1994A laboratory simulation was developed to provide mechanistic information about placer (nugget) gold development in the natural environment. To initiate the simulation, ionic gold was immobilized to a high capacity by Bacillus subtilis 168 (116.2 μg/mg dry weight bacteria) as fine-grained intracellular colloids (5–50 nm).
Southam, G, Beveridge, TJ
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Paradoxes of the placer gold economy
POWER AND ADMINISTRATION IN THE EAST OF RUSSIA, 2022The article is devoted to the study of influence of placer gold mining on the socio-economic processes in in the eastern areas of Russia on the example of the Trans-Baikal territory. Reconciliation of economic and environmental interests in the extraction of placer gold remains one of the most relevant in the field of natural resource management.
I. P. Glazyrina +2 more
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Economic Geology, 1994
Placer gold along the upper portions of Gold Creek, near Deer Lodge, Montana, occurs in Pliocene(?) fossil alluvial placers, Pleistocene till, and alluvium. The upper Gold Creek placers yielded an estimated 175 to 200 kg gold during 1890 to 1990. The gold probably originated in veins, skarn, or replacement deposits in Paleozoic and Mesozoic sedimentary
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Placer gold along the upper portions of Gold Creek, near Deer Lodge, Montana, occurs in Pliocene(?) fossil alluvial placers, Pleistocene till, and alluvium. The upper Gold Creek placers yielded an estimated 175 to 200 kg gold during 1890 to 1990. The gold probably originated in veins, skarn, or replacement deposits in Paleozoic and Mesozoic sedimentary
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Gold-ore and placer occurrences on Kamchatka
International Geology Review, 1971Late Miocene epithermal gold-silver analogues of the Far Eastern and Zabaykalian deposits and analogues of the Kolyma and Lena placers in Kamchatka, alongside other evidence, are indications of a high gold potential of the territory, here recommended as a new raw materials base for the Soviet gold industry.
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A Placer-Gold Evaluation Exercise
Journal of Geological Education, 1984An interesting application of applied geology is the location and evaluation of mineral deposits. This particular lab exercise allows the students to individually simulate the process of locating a placer gold paystreak on their own mining claim. Incorporated within the exercise is the arithmetic of computing the total value of the gold on the claim ...
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1991
In this chapter, ancient placers refer to deposits of Archaean and early Proterozoic age. Because each deposit may cover hundreds of square kilometres, they present economically attractive exploration targets. Individual ancient placer deposits like the Steyn/Basal placer in the Welkom goldfield of South Africa have produced in excess of 4500 t (metric
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In this chapter, ancient placers refer to deposits of Archaean and early Proterozoic age. Because each deposit may cover hundreds of square kilometres, they present economically attractive exploration targets. Individual ancient placer deposits like the Steyn/Basal placer in the Welkom goldfield of South Africa have produced in excess of 4500 t (metric
openaire +1 more source