The Elements of economic geology

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Monograph

Identifikator:: 1773832379

URN:: urn:nbn:de:zbw-retromon-172798

Document type:: Monograph

Author:: Gregory, John W. http://d-nb.info/gnd/11683014X

Title:: The Elements of economic geology

Place of publication:: London

Publisher:: Methuen

Year of publication:: 1928

Scope:: XIV, 312 S.; graph. Darst.

Digitisation:: 2021

Collection:: Economics Books

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Chapter

Document type:: Monograph

Structure type:: Chapter

Title:: Part II. Ore deposits

Collection:: Economics Books

10 ECONOMIC GEOLOGY alluvial grains of blende being deposited in limestone, any galena having been separated during the process; the zinc was concentrated and altered to silicate and oxide during the thermal metamorphism of the area. The Sullivan Mine, near Fort Steele, British Columbia, the greatest zinc mine in Canada, is a huge replacement deposit, in places 240 feet thick, in slate and quartzite. SILVER SILVER (Ag; at. wt. 107-7; sp. gr., 10°5 ; melting-point, (850° F.) is a white metal of a beautiful lustre and useful for jewelry, plate, and currency, as it does not oxidize at ordinary temperatures, and is hardened by addition of copper. It is the best conductor of heat and electricity, and is inferior only to gold in malleability. It was mainly used for coinage, and as its abandonment as the legal standard of value by many countries coincided with increased production, its price-fell from about 5s. an oz. between 1860 and 1870 to from 2s. to 2s. 6d. from 1900 to 1915. After the War, it rose to 17s. 6d. an oz., but has again fallen in 1927 to 2s. 1d. Silver is seldom mined independently, and most is obtained from ores of lead, copper, and gold. The chief silver-pro- ducing countries are the United States, Mexico, and Canada. Smaller supplies are obtained in Australia, Peru, Chile, Bolivia, Japan, Spain, and Portugal. The primary ore is a sulphide associated with lead and zinc, and as the problems of its ores are those of the metals with which it occurs, no special reference to them is necessary. Cosarr FreLp—Silver, however, occurs in some veins which are worked for it alone, or also for cobalt and nickel, The historic mines of this type are in the gneiss of Annaberg and Joachimsthal in Saxony. The most important now are at Cobalt in Ontario; ? the veins were discovered casually in a railway cutting in 1903 and regarded as ores of copper. In recent years the field has had an output of silver smaller tW. G. Miller, Ont. Bur. Mines, xix, pt. 2, 1913; Miller and C. W. Knight, Eng. and Min. Journ., xcv, 1913, Pp. 1129-33; J. M. Bell, Tr. LM. and M., xxxi, 1922, pp. 304-32, for S. Lorraine; W. H. Collins, G.S. Canada, Map 155 A; C. W. Knight, Ann. Rep. Ont. Dep. Mines, xxxi, 1922, pp. 321-58, gives summary of the literature. Microscopic study of the Ore, F. N. Guild, Zcon. Geol., xii, 1917, pp. 297-353, pls. X-XXV.

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