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

Usage license:: Get license information via the feedback formular.

Chapter

Document type:: Monograph

Structure type:: Chapter

Title:: Part II. Ore deposits

Collection:: Economics Books

26 ECONOMIC GEOLOGY ores of this type are in the Rocky Mountains, and have given rise to great secondary enrichments. Pvyritic Masses—Spain anp Mr. Lyeri—Historically the most famous of copper deposits are great lenticular masses of iron pyrites containing a small percentage of copper in South-western Spain—the Tarshish whence Solomon obtained copper for his temple. Mining was begun there in pre- historic times with stone tools, and continued by the Phoeni- cians, and the Romans who mined there on a colossal scale. After a prolonged interval, the field was re-opened about 1850. The ore is low in grade; most of the primary ore contains between -2 and ‘8 per cent. of copper, though some ore in the upper parts, probably owing to enrichment, con- tained 3 per cent. of copper. Much of the ore is used for the manufacture of sulphuric acid, the copper being recovered as a bye-product. The chief mines are near Rio Tinto and Tharsis, N. of the port of Huelva. The mining area is bounded to the N. by pre-Cambrian gneisses, schists, and crystalline limestones, in the Sierra de Aracena, and some Cambrian rocks. The mining fields are in a broad band of slates, shales, and quartzites of Silurian, Devonian, and Lower Carboniferous age. These rocks have been invaded by granites, quartz-porphyries, trachytes, and diabases, and some of them have been crushed and sheared by the Altaid mountain movements, which have given the sedimentary rocks a general strike of E. and W. All the igneous rocks have been regarded as intrusive (as by Vogt, Finlayson, and Edge); but the diabase, as near Zalamea, includes tuffs, agglomerates, and pillow-lavas. The ore deposits consist of many enormous lenticular or boat-shaped masses of iron pyrites. The ore is sharply separated from the country rock or the two pass into one another; the ore is usually massive, but is in places banded. The transition in places from clean slate or porphyry through rock mixed with pyrites into pure pyrites, and the microscopic evidence support the view that the ore was formed by the gradual replacement of the country. The ore-bodies near the margin in places contain inclusions of rock, which are exceptional in the middle, where the replacement has been complete. The upper part of the ore-body is sometimes richest in copper, which may have been concentrated from

Access restriction

Copyright

fullscreen: The Elements of economic geology

Monograph

Chapter

Table of contents

Download

Monograph

Chapter

This page

Image fragment

Citation links

Citation recommendation