Gossan

gossan

[′gas·ən] (geology) A rusty, ferruginous deposit filling the upper regions of mineral veins and overlying a sulfide deposit; formed by oxidation of pyrites. Also known as capping; gozzan; iron hat.

Gossan

(iron hat), a residual formation that occurs in the surface parts of ore (primary sulfide) deposits of copper, lead, zinc, and other metals as a result of chemical weathering and oxidation of the primary minerals of the ore body. Gossans consist primarily of iron oxides and hydrous iron oxides (goethite, hydrogoethite, hydrohematite, turgite), and as a result they are usually dark or light red, ocherous, or brownish red in color. The formation of gossans is associated with the oxidizing action of surface waters and is accompanied by the secondary enrichment of ore deposits. In the process of weathering, the sulfides of copper, silver, zinc, and other metals oxidize to easily soluble sulfates, after which they are leached and carried to deeper parts of the ore body. At the same time the iron in sulfurous compounds—pyrite, chalcopyrite, and other sulfides—is only partially removed in the form of a soluble salt (sulfate of iron oxide); most of the iron is oxidized and hydrated and remains in place in the form of hydrates of iron oxide (brown iron ores). These secondary brown iron ores, occurring as a result of the transformation of original pyritic and other ores containing iron sulfides, are what form the gossans near the earth’s surface. The depth at which gossans are found beneath the earth’s surface is usually restricted to the groundwater level and may extend to dozens or even hundreds of meters. In comparison with initial sulfide ores gossans are richer in iron in their upper parts and in gold in their lower parts. Contrasting strongly with the enclosing rocks, gossans serve as an important indicator in explorations for sulfide-ore deposits and in identifying the primary ores concealed in the depths.

REFERENCES

Smirnov, S. S. Zona okisleniia sul’fidnykh mestorozhdenii, 3rd ed. Moscow-Leningrad, 1955.
Saukov, A. A. Geokhimiia, 3rd ed. Moscow, 1966.

G. A. SOKOLOV

单词	gossan
释义	gossan gos·san G0204450 (gŏs′ən, gŏz-)n. An exposed, oxidized portion of a mineral vein, especially a rust-colored outcrop of iron ore. [Cornish gossen, from gōs, blood, from Old Cornish guit.] gossan (ˈɡɒsən) n (Mining & Quarrying) an oxidized portion of a mineral vein in rock gos•san (ˈgɒs ən, ˈgɒz-) n. a rust-colored, oxidized deposit along an exposed iron-bearing vein. [1770–80; orig. dial. (Cornwall) < Cornish, derivative of gōs blood; akin to Welsh gwaed] Gossan gossan [′gas·ən] (geology) A rusty, ferruginous deposit filling the upper regions of mineral veins and overlying a sulfide deposit; formed by oxidation of pyrites. Also known as capping; gozzan; iron hat. Gossan (iron hat), a residual formation that occurs in the surface parts of ore (primary sulfide) deposits of copper, lead, zinc, and other metals as a result of chemical weathering and oxidation of the primary minerals of the ore body. Gossans consist primarily of iron oxides and hydrous iron oxides (goethite, hydrogoethite, hydrohematite, turgite), and as a result they are usually dark or light red, ocherous, or brownish red in color. The formation of gossans is associated with the oxidizing action of surface waters and is accompanied by the secondary enrichment of ore deposits. In the process of weathering, the sulfides of copper, silver, zinc, and other metals oxidize to easily soluble sulfates, after which they are leached and carried to deeper parts of the ore body. At the same time the iron in sulfurous compounds—pyrite, chalcopyrite, and other sulfides—is only partially removed in the form of a soluble salt (sulfate of iron oxide); most of the iron is oxidized and hydrated and remains in place in the form of hydrates of iron oxide (brown iron ores). These secondary brown iron ores, occurring as a result of the transformation of original pyritic and other ores containing iron sulfides, are what form the gossans near the earth’s surface. The depth at which gossans are found beneath the earth’s surface is usually restricted to the groundwater level and may extend to dozens or even hundreds of meters. In comparison with initial sulfide ores gossans are richer in iron in their upper parts and in gold in their lower parts. Contrasting strongly with the enclosing rocks, gossans serve as an important indicator in explorations for sulfide-ore deposits and in identifying the primary ores concealed in the depths. REFERENCES Smirnov, S. S. Zona okisleniia sul’fidnykh mestorozhdenii, 3rd ed. Moscow-Leningrad, 1955. Saukov, A. A. Geokhimiia, 3rd ed. Moscow, 1966. G. A. SOKOLOV
随便看	doesn't miss it for the world doesn't miss much doesn't miss something for the world doesn't miss that for the world doesn't move a muscle doesn't move an inch doesn't/not to know from adam doesn't open her mouth doesn't open his mouth doesn't open my mouth doesn't open one's mouth doesn't open our mouths doesn't open their mouths doesn't open your mouth doesn't push it doesn't really matter doesn't stand an earthly doesn't stand for anything doesn't stand the ghost of a chance doesn't suffer fools gladly doesn't take kindly doesn't take no for an answer doesn't trust an inch doesn't trust as far as can throw doesn't trust as far as could throw

gossan

gos·san

gossan

gos•san

Gossan

gossan

Gossan

REFERENCES