Principles of Mining Valuation, Organization and Administration   By: Herbert Hoover (1874-1964)

Published by the McGraw Hill Book Company New York Successors to the Book Departments of the McGraw Publishing Company Hill Publishing Company Publishers of Books for Electrical World The Engineering and Mining Journal Engineering Record Power and The Engineer Electric Railway Journal American Machinist Metallurgical and Chemical Engineering

PRINCIPLES OF MINING

VALUATION, ORGANIZATION AND ADMINISTRATION

COPPER, GOLD, LEAD, SILVER, TIN AND ZINC

BY

HERBERT C. HOOVER

Member American Institute of Mining Engineers, Mining and Metallurgical Society of America, Société des Ingénieurs Civils de France, Fellow Royal Geographical Society, etc.

First Edition

FOURTH THOUSAND

McGRAW HILL BOOK COMPANY

239 WEST 39TH STREET, NEW YORK

BOUVERIE STREET, LONDON, E.C.

1909

PREFACE.

This volume is a condensation of a series of lectures delivered in part at Stanford and in part at Columbia Universities. It is intended neither for those wholly ignorant of mining, nor for those long experienced in the profession.

The bulk of the material presented is the common heritage of the profession, and if any one may think there is insufficient reference to previous writers, let him endeavor to find to whom the origin of our methods should be credited. The science has grown by small contributions of experience since, or before, those unnamed Egyptian engineers, whose works prove their knowledge of many fundamentals of mine engineering six thousand eight hundred years ago. If I have contributed one sentence to the accumulated knowledge of a thousand generations of engineers, or have thrown one new ray of light on the work, I shall have done my share.

I therefore must acknowledge my obligations to all those who have gone before, to all that has been written that I have read, to those engineers with whom I have been associated for many years, and in particular to many friends for kindly reply to inquiry upon points herein discussed.

CONTENTS.

CHAPTER 1.

Valuation of Copper, Gold, Lead, Silver, Tin, and Zinc Lode Mines

Determination of average metal content; sampling, assay plans, calculations of averages, percentage of errors in estimate from sampling.

CHAPTER II.

Mine Valuation ( Continued )

Calculation of quantities of ore, and classification of ore in sight.

CHAPTER III.

Mine Valuation ( Continued )

Prospective value. Extension in depth; origin and structural character of the deposit; secondary enrichment; development in neighboring mines; depth of exhaustion.

CHAPTER IV.

Mine Valuation ( Continued )

Recoverable percentage of the gross assay value; price of metals; cost of production.

CHAPTER V.

Mine Valuation ( Continued )

Redemption or amortization of capital and interest.

CHAPTER VI.

Mine Valuation ( Concluded )

Valuation of mines with little or no ore in sight; valuations on second hand data; general conduct of examinations; reports.

CHAPTER VII.

Development of Mines

Entry to the mine; tunnels; vertical, inclined, and combined shafts; location and number of shafts.

CHAPTER VIII.

Development of Mines ( Continued )

Shape and size of shafts; speed of sinking; tunnels.

CHAPTER IX.

Development of Mines ( Concluded )

Subsidiary development: stations; crosscuts; levels; interval between levels; protection of levels; winzes and rises. Development in the prospecting stage; drilling.

CHAPTER X.

Stoping