The prospector's field-book and guide in the search for and the easy determination of ores and other useful minerals

Front matter

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THE PEOSPECTOE'S

Preface To The Sixth Edition

The gratifying success of the fifth edition of The Prospector's Field-Book and Guide, unmistakably indicating the firm hold which it has on the confidence of Prospectors, has rendered necessary the preparation of this, the sixth edition. In doing this, the book has been carefully revised throughout, and where considered desirable, it has been enlarged. These revisions and amplifications add greatly, as it is believed, to the value and usefulness of the volume, and bring it fully up to date.

The work of revision has been undertaken by the same competent hand that so satisfactorily edited the second, third, fourth and fifth editions. As now presented to the public, it is felt to be a complete and thoroughly reliable guide and companion to the intelligent and enterprising searcher after ores and other useful minerals, including gems and gem-stones ; the very best that has ever been published in any language. It has been provided w T ith a thorough Table of Contents and an Index, ren-

VI PREFACE TO THE SIXTH EDITION.

dering reference to any subject in it prompt and easy.

In conclusion the publishers would add, that they confidently look for a sale of this edition, the largest in number that they have thus far issued, equal in its rapidity and extent to that of those which have preceded it.

H. C. B.

Philadelphia, Nov. 2, 1903.

PUBLISHER'S PREFACE TO THE SECOND EDITION.

The death of Dr. Osborn, two years ago, renders it necessary that the Publisher should prepare the preface to this revised edition of The Prospector's

FIELD-BOOK AND GUIDE.

The fact of a second edition of this book having been called for so soon after the publication of the large first edition, justifies the belief that it has supplied a public requirement. The task of revising the work has devolved upon thoroughly competent hands ; and whilst it has been aimed, by the insertion of further information regarding the subjects treated in the original edition, to make it still more acceptable to those for whom it was prepared, a new chapter has also been added on Petroleum, Ozocerite, Asphalt and Peat, together with a Glossary of Terms used in prospecting, mining, mineralogy, geology, etc.

While the work of revision has been done with conscientious care, under the supervision of the Publisher, it can hardly be hoped that it has been so well done as if Dr. Osborn, with his profound knowledge of the subject treated, had been alive to direct it for himself, and in his own manner.

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Vlll PUBLISHER S PREFACE TO SECOND EDITION.

Henry Stafford Osborn was born in Philadelphia, August 17, 1823, and died in New York City, February 2, 1894. He was graduated at the University of Pennsylvania in 1841 ; went abroad in 1843 or 1844 ; studied at Bonn, Germany, and at the Polytechnic Institution of London. Before the civil war he held the chair of Natural Science at Roanoke College, Va., and in 1866 accepted a professorship at Lafayette College, Easton, Pa. Leaving Lafayette in 1870, he became, in 1871, Professor in Miami University at Oxford, Ohio. In 1865 he received from Lafayette College the degree of LL.D.

In 1869 he published "The Metallurgy of Iron and Steel ; " in 1888, " A Practical Manual of Minerals, Mines and Mining ;" in 1892, the first edition of The Prospector's Field-Book and Guide, the success of all of which books has been pronounced.

Personally, Dr. Osborn was charming, full of information on a wide range of subjects, which he had studied thoroughly ; enthusiastic, amiable and just ; and the relations of his publisher with him during a quarter of a century, will ever be among the brightest and best recollections of that publisher's long career in business.

HENEY CAEEY BAIKD.

Philadelphia, January 15, 1896.

Preface To The First Edition

In the following pages we have attempted to present such a view of the whole subject of prospecting for the useful minerals that any liberally educated reader may fully comprehend our meaning. We have therefore explained special terms where we have thought it convenient to use them, and where the technically educated student would not need an explanation.

It must be understood that the subjects of chemistry, mineralogy, and metallurgy are introduced only for their practical bearing upon the ores in hand, or those sought for, and not for theory, or the philosophy of the operation, much as such theory or philosophy would please and instruct. The prospector must, therefore, refer to larger works if he desire to be instructed in the principles governing the sciences, the teachings of which we have frequently made use of.

We would suggest to any one intending to use this volume for practical work, to become acquainted with the whole book before attempting to use any special part alone. The object and construction have made it necessary to treat some

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X PREFACE TO THE FIRST EDITION.

special topics without repeating principles and methods already given in some part of the work, but which bear some relation to the topic under immediate consideration.

The Table of Contents and Index have both been carefully prepared, and being very fall, will make reference to any subject in the volume easy and satisfactory.

Oxford, Ohio, Jan. 5, 1892.

Chapter I. Preparatory Instruction

PAGE

Disappointment and loss caused by lack of knowledge by prospectors 1

Technical mineralogy, the first study of the prospector; Definition of a mineral; Definition of rocks; Principal constituents

of rocks 2

Quartz and its varieties; Feldspar 3

Most important kinds of feldspar 4

Micas; Most important species of mica 5

Amphibole, often called hornblende 7

Pyroxene, including augite 9

Chlorite 10

Talc; Serpentine; Elementary composition of minerals . ■ . 11 Calculation of the amounts of the elements going to make up any given mass; Definition of acids, bases and salts; Examples of minerals which are salts 12

Examples of silicates; Colors of minerals 13

Effect of the intermixture of coloring matter 14

Polychroism; Phosphorescence ... 15

Colors and forms under which native metals may appear . . 16

Cleavage; Fracture; Streak . . 17

Hardness; Scale of hardness 18

Manner of trying the hardness of a mineral; What may be learned from the test of hardness; Flexibility and elasticity;

Smell ... 19

Taste; Malleability; Ductility 20

Lustre; Definition of the various kinds of lustre 21

Specific gravity; Definition of the specific gravity of a mineral;

Weight and form of minerals 22;

(xi)

Xll CONTENTS.

PAGE

Importance of a knowledge of the characteristics of the rock associated with minerals; Desirability of a general knowledge of the manner in which the geologic rocks are laid down 23

Signs by which the name of the sedimentary rock may be determined; Horizons of the rocks 24

Movements of the earth's crust illustrated by a section showing contorted strata due to lateral pressure; Practical geology; Horizons sterile in ores ... 25

Horizons in the United States which abound in the useful metals; Classification of rocks; Definition of rocks .... 26

General sameness in the geological horizons throughout the world; Table showing the relations of certain rocks one to another; Igneous rocks 27

Metamorphic rock 28

The aqueous rocks; Sandstone, illustrated and described; Shale, illustrated and described; Granite 29

Varieties of granite 30

Granite with black mica and feldspar crystals, with quartz as chief base, illustrated and described; First indications of a deposit possessing economic value; Where metalliferous deposits should be looked for 31

Mode of occurrence of the valuable minerals and metal-bearing deposits of the earth; Lodes 32

Cross section of a formation or horse 33

Transverse section of solid quartz lode with casing; Beds and layers ... 34

Irregular deposits; Surface deposits 35

Selection of a spot for starting actual prospecting operations; Most likely localities of auriferous lodes; Source of gold in the right-hand branch of a forked river . . 36

The right-hand theory fully established by practical experience; Spots upon which the sun shines before noon richest in metal; Explanation of this theory; The color of the rocks as a guide to the prospector 37

Necessity of paying attention to the wash of rivers and creeks . 38

Pilot stones; Placers and placer gold £9

Character of placer diggings; Forms of alluvial deposits, illustrated and described 40

Estimating the value of alluvial claims 41

CONTENTS. Xlll

PAGE

Indicative plants; Vegetation indicative of lead and iron - . 42

Vegetation indicative of limestone, phosphate, silver, and zinc; Hints in looking for deposits where superficial deposits are known to occur . . 43

Mode of occurrence of gold in Australia and California; Mode of occurrence of other minerals; Points to be observed in examining a lode 44

Table showing the association of ore in metalliferous veins . . 45

Chapter II. The Blowpipe And Its Uses

On what chemical tests for minerals depend; Illustrations of the

character of changes brought about by chemical tests • 46

Requirements for blow-pipe practice; Manner of preparing dry

carbonate of soda 47

Borax and other supplies; Mode of using the blow-pipe ... 48 Practice with the blow-pipe by blowing upon a piece of charcoal; Colors of a candle flame ; Oxidizing and reducing flames

illustrated and described 49

Roasting; Illustration and practice in showing the characteristic power of the oxidizing and reducing flames; Mode of making

a platinum wire loop, illustrated 51

How to make a blow-pipe ... 52

Principal means of chemically testing minerals before the blowpipe; Blow-pipe experiments; Recognition of the presence of

metals by the color imparted to fused borax 53

Table of color indications 54

Mode of testing with carbonate of soda on charcoal 55

Observations and inferences from the above test 56

Test for sulphur and arsenic and other substances ; Tests in glass tubes 57

Chapter III. Crystallography

The composition of minerals indicated by their forms ; Classes

or systems of crystalline forms; Isometric system 59

The cube, illustrated and described; Variations of the cube . . 60 The octahedron and dodecahedron, illustrated and described; Tetragonal system 61

XIV CONTENTS.

The prism, illustrated and described; The zircon, illustrated and

described; Hexagonal system r . . 62

Forms of the hexagonal system, illustrated and described ... 63

Orthorhombic system .... 64

Monoclinic system; Triclinic or thrice inclined system; Illustrations of the different systems of crystallization 65

Distinction between the turquois, lazulite and lapis lazuli ... 66

The topaz and its crystallization 67

Meteoric iron ; Ruby and sapphire 68

Serious mistake of a Paris firm of jewelers; Localities of gems . 69

Chapter IV. Surveying

To measure heights which are inaccessible 70

To measure areas, illustrated by examples 72

To measure an inaccessible line, illustrated 75

The prism compass and its use 77

Chapter V. Analyses Of Ores

Wet Method; Preliminary examination; Detection of sulphur, arsenic and selenium ; Determination of native gold or silver. 79

Indication of copper; Detection of antimony and tin; Determination of manganese, alumina, magnesia, lime, zinc, cobalt and nickel 80

Determination of uranium, titanium and mercury; Detection of carbonates; Examination of sandstone 81

Qualitative analysis of ores; Directions for the wet method of analysis . . . . 82

Indications of silver, lead or mercury in the assay 84

Apparatus for making hydrogen sulphide, described and illustrated; Manner of cutting off the bottom of a bottle .... 85

The filtrate; What the precipitate may contain 87

Treatment of the precipitate; Precipitation of chromium oxide; Blow-pipe test for chromium; Precipitation of alumina; Definition of an excess 88

Precipitation of manganese, cobalt and nickel 90

^Establishment of the presence of mercury oxide and lead sulphate 91

CONTENTS. XV

PAGE

Indications of bismuth and cadmium, and of copper, sulphur

and gold 92

Detection of platinum and arsenic; Indication of antimony and

tin 93

Dry assay of ores; Crucibles; Scorifiers; The cupel; The muffle;

An assay furnace, illustrated and described 94

Brasquing; Portable assay furnace for field testing 95

Scales, weighing, etc . 96

Pulverization 97

Testing gold and silver ores; Cupellation 98

Flax for melting the ore in a crucible 99

Process of assaying gold quartz 100

Testing of lead ore, galena; Testing of copper, tin, mercury

and antimony ores 101

Directions for making an excellent fire lute 102

CHAPTEK VI.

Special Mineralogy, gold.

Importance of studying minerals from actual specimens ; Distribution of gold . 103

Occurrence of gold in sea water; Chief sources of the supply of gold ; Principal mode of occurrence of gold ; Composition of

native gold 104

Mexican rhodium gold ; Gold amalgam ; Black gold; Bismuth gold ; To detect a content of native gold in pyrites ; Crystallization of gold ; Gold crystals, illustrated ; Large lump of gold found at Forest Creek, Victoria, Australia, illustrated . 105 Physical properties of gold; Variations in the color of gold . . 106 Action of gold under the blow-pipe and towards acids .... 107

The bat ea, described and illustrated; Panning out 108

The cradle or rocker, described and illustrated Ill

The long torn, described and illustrated 112

Sluices and their construction 114

Hydraulic mining, described and illustrated . ... 115

Burning and drifting in the Forty-Mile District, Alaska . . . 118

Lode prospecting ... 119

Directions for making an amalgamating assay 120

XVI CONTENTS.

PAGE

Construction of a retort » 121

Calculating the amount of gold per ton an ordinary battery

might expect to save; Darton's gold test 122

Variation of the above test; Other forms and conditions of gold. 123

Placer gold; Gold amalgam 124

Geology of gold; Occurrence of gold in quartz; Original position of gold ... . . 125

Gold in granitic regions, illustrated by section showing the two conditions under which gold is usually found in rock and

drift 126

Significance of an ironstone ''blow-out;" Peculiar and seemingly irregular deposits of gold . . . 127

Origin of metamorphic rocks; Igneous rocks and their composition; Composition of metamorphic granite . . . . 129 Where the most paying gold is found; Gold in combination . . 130 To separate gold in metallic sulphides, for instance, iron pyrites;

Mode of making fuming nitric acid 131

Another method of detecting and separating the gold .... 133

What constitutes profitable gold mining ... 134

Method of separating gold which gives very accurate results . 135 Description of the Yukon gold district, Alaska; Dissemination of gold in Alaska; Where the profitable deposits have been

found 136

Derivation of the gold of the Yukon district 137

Extent of the gold-bearing rocks 138

Rule for ascertaining the amount of gold in a lump of auriferous quartz 139

Chapter VII. Tellurium, Platinum, Silveb

Tellurium minerals; Tellurium; Nagyagite, foliated or black

tellurium 141

Hessite; Petzite; Sylvanite or graphic tellurium 142

Value of tellurides; Platinum, its occurrence and properties;

Platinum in California and Oregon . . 143

Chief source of supply of platinum; Consumption of platinum

in the United States 144

Sperrylite and its occurrence; How to distinguish platinum;

Chemical test for platinum > 145

CONTENTS. XV11

PAGE

Separation of platinum from gold and other metals ; Preparation of stannous chloride 146

Iridium; Osmium; Palladium; Silver, its occurrence and properties ; Mispickel ; How to distinguish native silver before

the blow-pipe 147

Chemical test for silver 148

Derivation of most of the silver of commerce ; Other forms in

which silver is found; Silver glance or argentite 149

Ceragyrite or horn silver .... . . 150

Stephanite or brittle silver ore ; Red silver ore or ruby silver ;

Pyrargyrite 151

Bromic silver or bromyrite ; Valuing silver ores ; Geology of silver ores, illustrated by sections across the Comstock Lode and surrounding strata, east and west, and north and south,

and showing the mines and the surface 152

Non-metallic substances of the Comstock Lode 153

Extent and value of the Comstock Lode 155

Occurrence of silver at the Eureka Mines, Nevada; Peculiarity

of the limestone overlying the Eureka Mines 157

Geology of the Ruby Hill Mines ; The Emma Mine ; General geologic conditions in which silver ores are found 158

Chapter VIII. Copper

Copper, its occurrence and properties ; Manner of testing minerals containing copper 160

Natural combinations of copper; Cuprite, red copper ore or red copper 161

Chalcocite, copper glance or vitreous copper; Tetrahedrite or gray copper ore 162

Chalcopyrite or copper pyrites 163

Peacock ore ; Chrysocolla or silicate of copper ; Black oxide of copper 164

Malachite or green carbonate of copper ; Azurite or blue carbonate of copper; Variegated copper pyrites 165

Ores which furnish the bulk of the world's consumption of copper ; Geology of copper, illustrated by section of the copper bed at the Dolly Hide Mine, section of strata in Lake Superior copper region, and section of the Eagle Vein, Lake Superior 166

XV111 CONTENTS.

PAGE

Facts to be remembered to become ready in the detection of copper; Kocks with which copper is associated 1G8

Examination of specimens for copper ; Examination of the region in which copper is supposed to occur . .... 169

To obtain the per cent, of copper in an ore 170

Precautions to be observed in the assay of copper 171

Chapter IX. Lead And Tin

Lead, its occurrence and properties ; Galena ; Test for silver in

galena 174

Order of strata in the lead district of Wisconsin, Illinois and Iowa ; Geology and form of lodes of the galena ores illustrated by lead lode in micaceous slate in mine near Middletown, Conn 175

Carbonate of lead or cerussite, illustrated by section of strata in

California Gulch, Colorado . • 176

Sulphate of lead or anglesite ; Phosphate of lead or pyromor-

phite; Chromate of lead or crocoite 177

Lead ochre or massicot ; Lead-antimony ores ; Jamesonite ; Zinkenite ; The geology of lead illustrated by a section of

galena limestone 178

Circulation of water in lead veins 179

Deposit of lead in a fissure of the limestone; Chief sources of

lead in the United States 180

Tin; Assay of tin ore 181

Cassiterite or tin stone; Wood tin; Toad's eye tin; Stream tin. 182

Discovery of tin in Banca and Belliton .... 183

Tin pyrites (sulphide of tin); Occurrence of cassiterite in the

United States 184

Cassiterite as a type of a strongly marked class of deposits . . 185

Minerals most commonly associated with tin . 186

Wolframite, its properties and uses 187

Chapter X. Zinc And Iron

Zinc; Chief ores of zinc; Smithsonite or zinc carbonate; Calamine 188

CONTENTS. XIX

PAGE

Willemite; Zincite or red oxide of zinc; Sulphide of zinc,

sphalerite, or blende, or black jack . ." 189

Geology of zinc, illustrated by section of strata near Sparta,

New Jersey, zinc mines 190

Deposits of sulphide of zinc in Colorado and Montana; Blowpipe tests for zinc; Iron; Native iron; Chief ores of iron;

Magnetite, u polaric " or loadstone 191

Franklinite 192

Specular ore or red hematite; Brown iron ore or brown hematite, or limonite 193

Spathic iron ore or siderite; Black band ore 194

Chromic iron or chromite; Iron pyrites .... .... 195

Arsenical pyrites or mispickel; Geology of iron 196

Geological horizon around the iron ores of Lake Superior; Geologic regions in which iron ores are found 197

Section of Pilot Knob, Missouri; Use of the magnetic needle in

prospecting for iron 198

W. H. Scranton's report on the subject 199

Method of using the compass in searching for ore 200

Chapter XI. Mercury, Bismuth, Nickel, Cobalt And Cadmium

Mercury or quicksilver; Formation of amalgams 202

Cinnabar or sulphide of mercury; Metacinnabarite; Guadalcaza-

rite; Native amalgams 203

Quicksilver deposits of Almaden, Spain; Cinnabar at Idria,

Austria; Quicksilver-bearing belt of California 204

Bismuth 205

Nickel; Examination of nickel under the blow-pipe; Chief ores

of nickel; Smaltite; Nickel arsenide, "copper nickel" or

niccolite 206

Emerald nickel; Millerite 207

Sources of nickel at Sudbury, Canada; Foleyrite; Whartonite . 208 Jack's tin or blueite; Analysis of ores for nickel and cobalt;

Separation of lead 209

Separation of copper 210

Precipitation of the iron 211

Construction of a hydrogen apparatus 213

Separation of nickel and cobalt 215

XX CONTENTS.

PAGE

Garnierite and its localities; Cobalt 217

Smaltite; Cobaltite; Erythrite 218

Linnseite; Earthy cobalt, or cobalt wad, or asbolite; Geological

position of cobalt 219

Cadmium; Greenockite 220

CHAPTEK XII.

ALUMINIUM, ANTIMONY, MANGANESE.

Aluminium and its distribution; Minerals which serve as the

sources of the metal 221

Bauxite and its purification for the purpose of aluminium manufacture 222

Cryolite 223

Corundum and emery 224

Varieties of corundum; Localities for corundum in the United

States 225

Chief European sources of emery; Test for the quality of a sample of emery or corundum; Antimony and the forms in

which it occurs 226

Stibnite and its occurrence in the United States 227

Manganese; Classes of manganese ores; Wad; Pyrolusite . . . 228

Psilomelane; Manganese carbonate or rhodochrosite 229

Geological position or manganese 230

CHAPTEE XIII.

VARIOUS USEFUL, MINERALS.

Alum; Apatite or phosphate of lime 231

Coprolites 232

Arsenic; Native arsenic; Realgar 233

Orpiment; Asbestus; Barytes 234

Witherite; Borax . . 235

Clays; Classes of soft clays; Kaolin, porcelain clay, or China

clay 236

Pottery or plastic clay; Bole; Fuller's earth; Coal (mineral) . . 237 Anthracite (glance coal, stone coal); Bituminous coal; Brown

coal or lignite; Jet; Dolomite 238

Feldspar, orthoclase; Adularia; Moonstone; Sunstone; Aven-

turine; Amazon stone 239

CONTENTS. XXI

PAGE

Flint; Hornstone or chert; Fluorspar, fluorite; Graphite, plumbago, or black lead 240

United States localities for graphite 241

Mode of testing the purity of graphite; Gypsum 242

Alabaster; Satin spar; Plaster of Paris; Infusorial earth; Lithographic limestone 243

Meerschaum or sepiolite; Micas 244

Biotite or black mica; Muscovite or potash mica; Molybdenum. 245

Nitre or saltpetre; Rock salt 246

Occurrence of salt deposits; Deposit of rock salt in Petite Anse

Island, Louisiana 247

Slate; Sulphur 249

Method of estimating the sulphur available to tha acid maker

in a sample of pyrites; Talc, soapstone, or steatite 250

CHAPTER XIV.

PETROLEUM, OZOCERITE, ASPHALT, PEAT.

Occurrence of crude petroleum; Outfit and best time of the year for prospecting 252

Examination of the iridescent film on the surface of water; Indication of an outcrop of oil . . . 253

Tracing the source of the oil; The water test; Fresh fracture of oil-bearing sandstone 254

Color of traces of oil upon the surface of water in cooler weather ; Iridescent films in swampy puddles 255

Salses (mud volcanoes) and exhalation of natural gas as an indication of petroleum; Occurrence of oil in definite geological horizons 256

Occurrence of oil in beds or in veins; Tracing a thick seam or stratum of oil-bearing sandstone; Outcrops in a large mass of sandstone. 257

Data to be made in the sketch-map when promising out-crops of oil have been found, illustrated .... 258

Vein-like occurrence of oil, described and illustrated .... 259

Occurrence of oil in a maze of smaller and larger fissures . . . 260

Quality of the oil; Ozocerite and its occurrence; Ozocerite deposit in East Galicia, described and illustrated 261

Mineral resins closely allied to ozocerite 262

Retinite; Elaterite; Pyropissite; Properties of ozocerite . . . 263

XX11 CONTENTS.

PAGE

Native asphalt or bitumen; Most remarkable deposits of asphalt; Asphalt in California and other portions of the United States 264

Peat 265

CHAPTER XV.

GEMS AND PRECIOUS STONES.

Occurrence of gems and precious stones in the United States;

Comparatively little value of many gems 266

Occurrence of diamonds and gold in the same alluvial deposit. 267 Use of the dichroiscope in distinguishing gems . . . . 268

Diamond; Occurrence of diamonds in India, and in Borneo . • 270 Diamonds in Brazil; Carbonado or black diamond; Minerals

associated with the diamond in South Africa 271

The diamond-bearing ground at the Kimberley Mine, South Africa; Occurrence of the diamond in the Ural, Australia,

New Zealand, and in the United States 272

Natural surface of the diamond ; Color of the diamond .... 273

Properties of the diamond 274

On what the value of the diamond depends 275

Some of the largest diamonds, illustrated ; The Koh-i-noor ; The Orloff; The Grand Duke of Tuscany or Florentine; The

Pitt or Regent; Sapphire . . 276

Ruby and its varieties ... 277

Topaz and localities for it in the United States 278

Beryl or emerald; Phenacite 279

Zircon; Garnet and localities for it in the United States . . . 280

Tourmaline 281

Epidote; Opal and its varieties 282

Turquois, and localities for it in the United States 283

Agate and its varieties 284

Chalcedony; Chrysoprase; Carnelian and sard; Jasper; Bloodstone or heliotrope . 285

Rock crystal ; Amethyst ; Rose quartz; Smoky quartz; Yellow

or citron quartz, or false topaz . 286

Onyx and sardonyx; Cat's eye; List of gem-stones compiled by

Mr. George F. Kunz 287

List of gem-stones known to occur in the United States .... 288

CONTENTS. XX111

PAGE

List of species and varieties found in the United States, but not met with in gem form ; List of species and varieties not yet identified in any form in the United States ; List of gemstones occurring only in the United States 289

Table of characteristics of gems 290

Appendix

Prospecting by means of electricity 293

Weights and measures ; Basis of British weights and measures. 295 Weights and measures of various nations; English length ; Particular measures of length; Surface measure 296

Surface measure in feet; Solid measure; Troy weight; Avoirdupois weight; Weight by specific gravity; Method of finding

the weight of masses without the use of scales 297

How to find the specific gravity 299

Special weights, etc > . . 300

French measure; Length; Surface; Solid measure; Weight . . 301 Specific gravity of metals, ores, rocks, etc. ; Ores associated with

gold and silver; Other ores 302

Specific gravity of minerals of common occurrence; Average in

cubic feet of a ton weight of various materials 303

Assay of gold by the touchstone . 304

Estimation of gold in alloys 305

Standard value of gold in different countries; Power for mills . 307

Boring; Diamond drill 308

The chemical elements, their symbols, equivalents and specific

gravities £09

To find the proportional parts by weight of the elements of any substance whose chemical formula is known; Common names

of chemical substances 311

Prospectors' pointers 313

Glossary of terms used in connection with prospecting, mining,

mineralogy, geology, etc . 315

Index 3£5

THE

PROSPECTOR'S FIELD-BOOK AND GUIDE.