Kritische Studien zum wirtschaftlichen Problem des Zwei- und Dreischichtensystems in Hochofenbetrieben

Bibliographic data

Monograph

Identifikator:: 1827036052

URN:: urn:nbn:de:zbw-retromon-221296

Document type:: Monograph

Author:: Uribe, Antonio José http://d-nb.info/gnd/1055157581

Title:: La defensa social

Place of publication:: Bogota

Publisher:: Impr. Nacional

Year of publication:: 1929

Scope:: 50 S.

Digitisation:: 2022

Collection:: Economics Books

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

Document type:: Monograph

Structure type:: Contents

Collection:: Economics Books

THE SCOPE OF ECONOMIC GEOLOGY 5 found. The nickel ore of Sudbury and the silver veins of Cobalt were both cut during railway construction. Neverthe- less most important mining fields have been discovered by Systematic search. When a mining prospector visits an unknown country he would regard iron ore, coal, oil shale, or ordinary earthy minerals as useless until the country has been settled ; he would look for gems and the more valuable Metals, such as gold, platinum, tin, and copper. His search would usually begin by examining the local gravels, If their pebbles consist of unaltered limestone or sandstone the indication would be unfavourable ; but schists, traversed by quartz-veins, and abundant quartz pebbles would be encouraging. The prospector would use a * tin-dish” which is a basin of tinned iron with a flat base, and a rib on one side. The usual size js I6 to 20 inches in diameter at the top, 10 to 12 inches at the bottom, and 2} to 3 inches deep ; it holds, when heaped up, about 20 to 25 lb. of earth, which is washed by pouring water into the dish, stirring the gravel by hand and throwing aside the pebbles as they are cleaned of sang and mud. The prospector pours out the water as often as it becomes muddy, and at the same time gets rid of the fine sand until only the heavier material is left. This residue is spread by a flow of water along one side of the floor of the dish; the constituents are left in a streak in order of their specific gravity, the heaviest at one end and the lightest at the other. If gold is present it is conspicuous by its bright color, and as, owing to its malleability, tiny particles are hammered into broad flakes which are known as colors. They are too small to be weighed in the field, but On an average 35 ‘‘ colors” weigh one grain. As the tin dishful is from 155 10 thy of a cubic yard the prospector, by counting the colors, can calculate the amount of gold per cubic yard or ton. The other materials in the residue would probably include crystals of zircon, heavy silicates, and grains of “black sand,” ie. oxide of iron. The glassy grains would be examined for gems, and would be tested by Pressing beneath a piece of wood against a piece of glass or quartz. If a grain scratches quartz it is probably one of the gems. If this washing yielded nothing of value the prospector would follow a river inland, testing the gravels along its

Access restriction

Copyright

Metadata: Der Weltverkehr und seine Mittel

Monograph

Contents

Table of contents

Download

Monograph

Chapter

This page

Image fragment

Citation links

Citation recommendation