The Elements of economic geology

Bibliographic data

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

ORES OF FIVE MINOR METALS 127 fragments cemented by veins of stibnite; lenticular bodies of ore show the tendency towards nodular masses. Tegengren reports that the stibnite is a replacement of fractured rock. An essentially similar process has formed the ores at the Chiang-Ch’i-lung and Pan-Ch'i Mines, which are both in the basin of the Tze River, a southern tributary of the Yangtze- kiang in Hunan. At both localities the rocks, in addition to having been folded and fractured, have been invaded by Intrusive rocks which appear to have no essential connection with the ores. The antimony at the Chiang-Ch’i-lung Mines Is replaced at a depth of from 300 to 400 feet by pyrites. The nodular masses of antimony ore are replacements by solutions moving vertically, as they are independent of the rocks in which they occur. The concentration is due to the solubility of stibnite in water at 180° F.; hence small particles are readily dissolved, and the sulphide remains in solution until near the surface, where it is deposited in a concentrated form by the replacement of various rocks. The amount of antimony in the lodes generally falls rapidly In depth, and it is replaced by various minerals such as ores of zinc in Arkansas, pyrites in some Chinese deposits, and scheelite (CaWO,) in Sardinia. ARSENIC Arsenic (As; at. wt, 75; sp. gr., 57; vaporization, 800° F.; volatilization begins at 212°) is very widely dis- tributed as it is a constituent of 130 or about 12 per cent. of the known mineral species. Its chief ores are mispickel Or arsenical pyrites (FeAsS), which contains 46 per cent. of arsenic; realgar (AsS), and orpiment (As,Sg). Its main uses are to decolor glass and as a pigment, a drug, an insecti- cide and weed-killer, and preservative in arsenical soap. During the War it was used to harden shot, owing to the scarcity of antimony. It is usually carried into its ores in solution, but it enters tock cavities as vapour and is deposited on the roof as small crystals of realgar. It is often associated with copper, and was produced from the upper part of the Cornish copper zone, and was found, as at Dolcoath, at a depth of 500 to goo feet: it is deposited after tin. as it occurs in the middle crust of

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