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

CHAPTER IX ORES OF IRON [RoON—HiIsTORY AND QUALITIES Iron (Fe; at. wt. 56: sp. gr., 7-5 to 7-8; melting-point, 2900° F) is the most indispensable of all metals. It is fortunately plentiful, for it is the most abundant constituent of the earth, varying in rocks from less than I per cent. in ordinary granite up to 30 per cent.; the barysphere may contain 80 per cent. Native iron is rare, but is found in meteorites, and where iron oxide has been heated in the pre- sence of carbonaceous material; it was probably first ex- tracted from its ore by the same reaction when grains of iron oxide in.sand were accidentally reduced by hot charcoal. This process was apparently first used by negroes in tropical Africa. Iron was used in Egypt in 7000-6000 B.c., according to Flinders Petrie (F. Iron and St. Instit., 1912, i, pp. 182-3), but did not come into general use there until 500 B.C., when It had long been the common domestic metal in China. Its Introduction to Northern and Central Europe is assigned to about 600 5.c. According to most archeologists man worked bronze earlier than iron ; but metallurgists insist that some use of iron preceded that of bronze (St. J. V. Day, Prehistoric Use of Iron, 1877, p. 3, etc.; J. Percy, Metallurgy. Iron and Steel, 1864, pp. 873-4; L. Beck, Geschichte Eisens, 1, 1884, pp. 78, 82-4). The widespread distribution of iron and its conspicuousness as the chief colouring matter in rocks are aided by the solu- bility of its salts and the readiness with which iron is oxidized Into rust. The latter quality, though the greatest industrial defect of iron, has rendered it available as a cheap metal Owing to its concentration into high-grade ores. The mobility of iron is aided by its two oxides (ferric, Fe,0, with 70 per [29

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