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 I. Introduction

Collection:: Economics Books

THE SCOPE OF ECONOMIC GEOLOGY 7 present in the district traces of them should be found, such as grains of tin ore, which would probably be associated with fragments of black tourmaline (schorl) and topaz. If the miner has failed to find in the alluvial beds any gold, platinum, tin, or gems, he would turn to the hills or areas of exposed rock in the hope of finding other minerals. He would search for quartz or calcite, and in them for metallic minerals, which in most veins would originally have been sulphides. In a moist climate the sulphides near the sur- face are oxidized and removed in solution. Some of the iron would probably have been deposited as iron oxide, staining the vein brown or red. Sulphides of copper would have been dissolved, and possibly redeposited as the green carbonate, malachite, or as plates or strings of native copper. If the vein contained lead the top of the lode would probably contain cerussite, the carbonate of lead. Iron-bearing lodes and seams of coal and oil shale would be noted as resources available for the future. Lodes con- taining the precious metals or the more valuable of the base metals, copper, lead, zine, nickel, etc., would be prospected to determine their grade or proportion of valuable constituents. STRUCTURE OF Loprs—The simplest form of lode is a metalliferous vein traversing the bedrock, which is technically known as the country, Veins are sheet-like in form and range from horizontal to vertical. Each lode or vein is bounded by two walls or cheeks, of which the upper is known as the hanging-wall, and the under as the foot-wall. The horizontal direction of a vein is its strike or course, The inclination from the horizontal is the dip (Fig. 1) ; the inclination from the verti. Fie. 1.— Diagram cal is usually the more useful measure- oF 4 Lope. ment, and is the underlay or hade. A AB, strikes, Bo, lode may consist of a single vein or may be i Aug ’ ’ compound. A compound lode consists of a series of veins, either of the same or different materials; the veins may be parallel, or divergent, or in a network, or may be mixed with masses of broken country. The simplest lodes are those deposited in fissures, which are of two chief kinds. The first are clefts of which the walls have been pulled apart

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