The laws which regulate the deposition of lead ore in veins; illustrated by an examination of geological structure of the mining districts of Alston Moor

Front matter

fyxmll Uttivmitg ^itotg

-S^mgkHiNG L/BPA^v

The laws which regulate the deposition o

Preface

To collect, arrange, and harmonize the experience of many generations on snbjects relating to the knowledge of external nature is a difficult task, but more especially when the phenomena are removed from ordinary observation and seen only by few individuals, and at various periods of time.

This is peculiarly the case with everything relating to veins and the metallic deposits they contain. It is often difficult, and sometimes even impossible, to obtain information, and when obtained, it is not unfrequently mixed with error, the result of defective or bad observations. Men's ideas of a rich mine vary much, and generally fluctuate with the marketable value of the metal produced. Large profits might be obtained from mines of lead, when lead sells at twenty-five pounds per ton; but should it realize only twelve pounds per ton, the same mines might be considered as utterly worthless. Again, they vary according as the veias happen to be hard or soft, for it is manifest, that large profits might accrue from lead ore scattered in the rider of a soft vein, which would not repay the cost of extraction from that of a hard one ; and vmless such conditions be properly allowed for, in the investigation, it must necessarily viu PREFACE.

affect our ideas of the constancy of Nature's laws, or rather the connexion between the cause and the amount of effect produced.

For inquiries relating to this connexion the comparative richness of a vein may be indicated by two methods, either by registering the quantity of lead ore produced per square fathom of the vein irrespective of its width, or by the quantity produced per solid fathom of vein mineral worked out in order to obtain the ore exclusive of the rocky portions of pure limestone, sandstone, &c., whether comprehended in the middle of the vein or worked from its sides. In a new mining field perhaps both should be carried out in practice. I am not aware that either of these methods has ever been attempted in Alston Moor, consequently the colours upon the map which accompanies this work relate more to the comparative mercantile value of the veins than to the amount of lead ore actually deposited in them. Could the veins have been coloured so as to denote the exact quantities of lead extracted, and those in proportion to the space excavated, my impressions are that the connexion between the cause assigned in the following pages, and the effect would have been exhibited in a still more striking manner.

The map is formed by the reduction and combination of a number of general plans of mines, made by various individuals and at different periods of time. Some portions of it are very correct, while others are not so, more especially Mr. Fydell's portion of the Priorsdale Manor, and those based upon the survey of Alston Moor, completed in 1777. Eespecting the mines in Kilhope I have not been able to obtaia either correct plans or much information. Most of the map has, however, been carefully collated with recent surveys, and the most defective

PEBFACE. ix

portion is sufficiently accurate to illustrate the laws relating to the distribution of lead ore in veins, and the theory of causation which comprehends the whole.

For the lines denoting the outcropping of the strata I alone am responsible ; they were carefully sketched upon pocket maps during my geological rambles over the district.

While prosecuting this inquiry I have experienced the greatest kindness from the proprietors and agents of the mines in Alston Moor. The manorial plans belonging to the Greenwich Hospital were kindly placed at my service by Mr. Paull and his late father. Loans of maps have been granted me by various parties, and valuable information has invariably been given me with the greatest willingness and kindly feeling. I avail myself of this opportunity of tendering my most grateful acknowledgments to all these parties, and more especially to Mr. Walton of Greenends House, Mr. Cain, Newhouse, Weardale, and Mr. Nevin, Carshield House, West AUendale. Had it not been for the information furnished me by these three gentlemen a great portion of the map could not have been constructed.

Contents

PAGE

Tntrodi'ction .. .. .. .. .. I

Book I

OF THE FOKMATION AND GEOLOGICAL STRUCTURE OF THE MINING DISTRICTS OP ALSTON MOOR.

Chapter I

OP THE LAWS WmOH HAVE REGULATED THE UEPOSITION OF THE MOUNTAIN LIMESTONE IN GREAT BRITAIN.

The analogy of causea now in operations — Key to past events . . . . . . 13

Of the sedimentary rocka situated below the Mountain Limestone . . 14

Of the change in the constituent parts of the Mountain Limestone . . Of the correspondence of its thickness in Derbyshire and Alston Moor The law of ita deposition . .

Its great development in South Wales Its character in Scotland

Probable position of the Continent from the waste of whioli the materiala

Chapter II

OF THE ELEVATION OF THE ROOKS OF ALSTON MOOR TO THE POSITION THEY NOW OCCUPY, ASO THE LAWS WHIOH HAVE REGULATED THE DENUDATION OP THE COUNTRY.

The equable subsidence of the sea-bottom at the time of the deposition of the

Carboniferous system . . . . ■ . . . . . . . . . . . 26

This system brought to a close by the elevation of the land . . . . . . 27

The laws of elevation and the formation of anticlinal axes . . . . . . 28

The effect of these upon the denudation of the couutiy . . . . 30 xu CONTENTS.

Of the general dip of the strata . .

Two denudation hypotheses — Oataclysmal one not tenable

Of the laws of denudation by oceanic and fluvial agency

Of the effects produced during the glacial epoch

The formation of the valleys chiefly due to breaker action

PAGE

30 36 37 47 48

Chapter III. Op The Laws Which Eegtilate The Fobmation And Dibection Of Veins

The minor streams of the country do not flow on the line of the strong cross

veins— nor upon that of the Great Sulphur vein .. .. .. ..49

The form and outline of the hills seldom affected by veins . . . . . . 50

Two tlieories on the formation of veins .. .. .. .. .. ■■ „

No veins of Alston Moor formed by the shrinking of the enclosing rocks . . 51

Veins quite distinct from joints . . . . . . . . . . • ■ . . 52

Hypothesis respecting the formation of joints .. •• .. .. ..53

Three distinct kinds of mineral veins . . . . . . . . . . . . 55

The Great Sulphur vein and the Whin Dyke, each mi generis ■■ ■■ „

Period of formation of the former in relation to the cross veins .. .. 56

Chapter IV

OF THE LAWS REGULATING THE FORMATION AND DIBECTION OF THE EAST AND WEST VEINS.

Brief description of the principal veins . . . . . . . . . . . . 61

Law of their formation . . . . . . . . . . . . . . . . 65

Connected in causation with the anticlinal axes . . . . . . . . . . 69

Must have been in existence before the formation of the valleys . . . . „

And before the elevation of the land to its present position . , . . . . „

No indications of violent volcanic agency since their formation . . . . 71

Chapter V. Of The Formation Of Alston Moor And Coal Clecgh Cross Veins

Found of all degrees of magnitude

Brief description of the principal cross veins

Of the law and relative date of theil formation . .

Werner's doctrine of intersections

Supposed to be later formed than the east and west veins

72 73 76

it

CONTENTS. xiii

PAGE

Eeasona why they cannot be SO .. .. .. .. .. .. .. 79

Must have been formed contemporaneously with or anterior to the east and

Their non-relation to axes of elevation . . . . . . . . . . . . 83

Effect upon the position of the stiata ,

Changes supposed to have been effected at the time of the formation of the

Chapter VI. Of The Quaeteb Point Veins Op Alston Moob

In the upper part of the district these veins are weak

Were probably in existence at the time of the formation of the east and west

veins Later formed than the cross veins . .

Concluding Aphorisms

Book II

OF THE LAWS WHICH REGULATE METALLIFEROUS DEPOSITS, ILLUSTRATED BY AN EXAMINATION OF THE LEAD VEINS OR LODES OF ALSTON MOOR.

Chapter I. Op The Mode Op Pkoseotjting The Inquiky

Brief resume of the last book . . . . . . . . . . . . 95

Lead ore not deposited throughout the whole extent of the veins . . . . „

As the veins have not always been filled with minerals and metaUic substances, their deposition must be the result of certain antecedents . . . . 96

The laws which have regulated the distribution of metallic ores may be different from those relating to its origination . . • . . . ■ ■ • ■ >, Two theories . . . . . . . . . . • . . . ■ • • • - ■ »

A knowledge of the distribution of metallic ores might prove more useful than a knowledge of its origination . . - . . . . . ■ • ■ ■ ..

The experiments of Becqueral and others throw no light on the art of mining, nor upon the source from whence the ores of metals are derived . . 97

XIV CONTENTS.

PAGE

The amount of lead ore in the same vein and strata varies more than that of

Veins in Alston Moor are richest at the greatest distance from Plutonic

Lead and other ores found in situations where there could be no sublimation

Instances in shells, nodules, &c. . • • • • . . • • ■ • ■ „

May be regarded as instantiss cmeie . . . . . . . . • • . . 100

The cause of its deposition must be proportional to the effect produced . • 101

CHAPTER II. OP THE CONDITIONS COimECTEU \V1TH BAMPGILL VEIN

Laws of succession best studied where the phenomenon exists in the greatest intensity . . . . . . . . . . . . . . . • . . . . 102

The phenomenon, lead ore exists in Rampgill vein in the greatest intensity . . 103

Description of the piano-section . . . . . . . . . . . • „

General view of the conditions of the dip of beds in the rich and poor portions of this vein . . . . . . . . . . . . . . . . 103

The largest quantities of lead ore found at the intersections of quarter point veins • • . ■ . . . . . . . . . . . . . . 105

A circulation promoted by these to and in the vein, the unproductive portion unfavourable to a circulation . . . . . . . . . . . . . . „

A circulation prevented in great depths by thick beds of shale, in the upper strata by the dislocations of the strong cross veins . . . . . . . . 106

The functions of the conditions differ from each other ; those connected with the rich portion being favourable to a circulation, the other not so . . 107

Analogy of the former to the functions of life in vegetables and animals . . „

CHAPTBE III.

OF THE LAWS BEGULATINfi THE DESCENT OF WATER BELOW THE SUBPAOE OP THE EABTH.

Two theories ; the one supposes that water rises from the interior of the earth ; the other, that it is precipitated from the atmosphere — the former

The heat of the sun and gravity cause a compound circulation on the earth's

Its effects upon animal and vegetable life . . . . . . . . . . Ill

The quantity of water precipitated on the hills of Alston Moor . . . . 113

The ^ret g(e^^era^a^« regulating its descent into the earth .. .. ..114

The second ditto ditto . . . . • . „

The third ditto ditto 115

The /owft ditto ditto H7

T:\iefifth ditto ditto 119

CONTENTS. XV

Chapter IV. Op The Decomposition And Change Effected On The Books Forming

THE SIDES OF VEINS. PAGE

Difference between the action of water upon the surface and in the interior

Composition of the atmosphere, its impurities combine with rain water . . 122

Change produced upon living organisms by these impurities . . . . . . 123

The action of water upon roolrs at the surface always detersive . . . . 124

Contents of veins equally subject to decomposition as the enclosing rocks . . „

Limestone under certain conditions especially subject to change . . . . 125

The action of water below the earth's surface reproductive as well as destructive . . . . . . . . . . . . . . . . . . . . 128

Kain water holds carbonic acid in solution ; the latter plentifully found in

Connected by some law with the state of the atmosphere . . . . . . 131

The important part it plays in disintegrating rocks . . . . . . . . 133

Instances of its effects — limestone at Clermont, Small Cleugh, Long Cleugh, Tyne Bottom, Ashgill Field, Eampgill, Holey Field, Coal Cleugh, &c. Mines .. .. .. .. .. .. .. .. .. „

Chapter V

OF THE DEPOSITION OF VEIN-MINEBALS, AS CABBONATE OF LIME, BAETTES, ETC. IN THE OPEN SPACES IN VEINS.

Resume of the preceding chapters.. .. .. .. .. .. .. 141

Question whether vein-minerals are related in kind to the enclosing rock . . 142

Fluor-spar found in veins whose sides are formed of Slate SUls, Firestone, &c. „

Less of it found in the Little Limestone . . . . . . . . . . . . 148

The greatest variety of minerals found in veins in the Great Limestone . . „

In the strata below the Great Limestone quartzose minerals predominate . . 144

But the veins occasionally contain much carbonate of lime . . . . • • „

Carbonate of lime, barytes apparently less orderly arranged and less dependent upon the enclosing rock than might have been expected . . . . 146

CHAPTER VL

OP THE CONNEXION BETWEEN THE LAWS BEGOLATING THE DESCENT AND dBCHLATION OF FLUIDS, AND THE DEPOSITION OF LEAD ORE IN THE VEINS OF ALSTON MOOK.

Difference in the metalliferous character of the upper and lower part of the Mountain Limestone .. .. .. .. .. .. .. ■. 150

The inquiry, in the first instance, restricted to the upper part . . . . 151

If the deposition of lead ore is dependent upon circulating fluids, there must be a connexion between the laws regulating their descent and the amount of lead ore deposited . . . . . . . . . . . . . . . . „

XVI CONTENTS.

PAGB

Notwithstanding that deposits of lead ore appear irregularly distributed in patches, they must be subject to law and order . . . . . . ..152

Necessary to divide the district into portions comprising groups of veins . . „ Of the connexion between laws of hydrous agency and the ore deposits in Middle Oleugh veins . . ■ . . • . . • • . . • • 153 And in the cross veins of the same district .. .. .. .. .. 154

Correspondence found to exist . . ■ • • . - • . . . • . • 156

The same veins on the east side of Carrs vein . . . . . . . . • . „

Lead ore has been removed from Long Oleugh and Middle Cleugh second

sun veins in the Firestone stratum by oxygenous fluids . . 158

Connexion between the laws of hydrous agency and the ore deposits in the east and west veins on the west side of Carrs vein . . . . . . . . 159

These east and west veins cease to contain lead ore in the Great Limestone as they pass under the summit of Middle Fell . . . . . . . . 160

Conditions connected with the cross veins bringing them under the same laws of hydrous agency as the east and west veins . . . . . . • • ,,

Of the deposition of lead ore in flats .. .. .. ..165

Exemplifications of the ^/6A Zaw .. .._ .. .. .. .. .. 166

General views depending upon the configuration of the district . . . . 167

CHAPTEE VIL

OP THE CONNEXION BETWEEN THE LAWS OE HYDROUS AGENOT AND THE DEPOSITION OE LEAD OBE IN VEINS ON THE EAST SIDE OE THE KENT BIVEE.

Non-correspondence between position of anticlinal axis and the heaven's water division . . . . . . . . . . . . 168

Modifies the effect of the first law . . . . . . . . . . . . „

On the east side of Bridge Cleugh this modifying condition does not exist . . 169

The lead ore deposits in EampgiU and High Coal Cleugh vein vary as the conditions . . . . . . . . . . . . . . . . . . 170

EampgiU sun veins favourably situated for mineralization with lead ore under the fourth law .. .. .. .. .. . . 171

Correspondence between absence of lead ore in all the veins and the unfavourable position for circulation of fluids under the fifth law . . . . . . 172

Lead ore deposits in Scalebum vein and flats depend upon the same conditions as EampgiU vein, except in the upper strata of Slate Sills and Firestone 173

Of the unfavourable position of the cross veins on the north side of Scalebum vein . . . . . . . . . . . . . . . . . . . . 174

Connexion between the laws of hydrous agency and the deposits of blende and lead ore in Guddamgill vein .. .. .. .. .. .. 175

Connexion, &c., and the lead ore deposits in Brownley Hill veins Ditto ditto Foreshield veins

Ditto ditto Blaygill and Thomgill veins

Ditto ditto Clargill and Aleburn veins

Eesults

178 182 183 185

CONTENTS.

XVll

CHAPTER Vm.

OP THE CONNEXION BETWEEN THE LAWS OF HYDROUS AGENCY AND

THE DEPOSITION MIDDLE FELL.

OF LEAD ORE IN VEINS TRAVERSING THE MOUNTAIN

This district not much affected under the fifth law

Middle Fell isolated from the east and west range of mountains by Caple Cleugh and Ashgill Burn. The fluids circulating in it entirely dependent upon those which fall directly from the atmosphere . . Laws of hydrous agency, and correspondence of the lead-ore deposits in the two Caple Cleugh veins . .

Ditto Hangingshaw, Cowslitts, and Peatstack Hill veins

Ditto Longholehead and Black Ashgill veins

Ditto Dowgang veins ; modification ot first law

Ditto Nenthead Fields and Greengill East-end veins . •

Ditto Grass-field veins

Ditto GaUygill Syke and Gallygill WeU veins - .

Ditto HudgiU Bum veins and veins lying to the north of these

Ditto Holeyfield, Famberry, and Natti'ass veins

Ditto Flough Edge and Dowpot Syke veins

Ditto Craig Green veins . .

Ditto Black Syke and Pletoheras veins . .

Ditto Cowper Dyke Heads veins • .

Ditto Benty Field and the Browngill veins

Ditto Wellhope Knot vein . .

Form of the amolybdic groimd as affected by the different laws

And lastly, by the removal of the lead ore from the veins by atmospheric

agency -

n

199 200 201 203

CHAPTER IX.

OF THE CONNEXION BETWEEN THE LAWS OF HYDROUS AGENCY AND THE DEPOSITION OF LEAD ORE IN THE OTHER PORTIONS OF THE UPPER STRATA SHOWN UPON THE MAP.

Decomposed and broken state of the Great Limestone near the surface, in the

ground between Nagg's Head and the Great Sulphur vein 206

Weak character of the veins which cross LittlegiU Bum 207

Of Windy Brae vein . . . . • • • ■ • • • ■ ,,

Of Broad Mea and Comrigga veins

Of veins traversing the Great Limestone on the north side of the Great Sulphur vein . . • . • ■ • • • • • • • ■ • • ■ • ■■ ,1

Of Cross Fell veins 208

Variation in the amount of lead ore in different parts of the Great Limestone

C xvill CONTENTS.

CHAPTER X.

OP THE CONNEXION BETWEEN THE LAWS OP IIYDK0T3S AGENCT, AND THE GEE DEPOSITS IN THE VEINS TKAVEESING THE " LOWER BEDS."

PAGE

Greater variation in position of lower than upper beds places the veins under two conditions .. .. .. .. .• •. .. .. .. 211

The greatest number of trials made in the veins near the surface . . „

Of the Dowgang veins in lower strata near the surface . . . . . . 212

Of the Brownley Hill and Grass Field vein .... . . . . . . • • „

Of the Neutsberry Haggs vein . . - - . . . . . . . . 213

Of the Gallygill Well vems

General unproductiveness of veins in Middle FeU . . . . . . . . 214

Ditto ditto Tyneliead Manors 215

Of Providence or Tees-aide vein . . . . . . . . . . . . . . „

Of Sir John's vein — Copper ore .. .. .. .. .. .. .. 216

General poverty of the veins in this district ,

Of Kodderup Fell veins . . . . . . . . . . . . . . 217

Of the veins crossing Cashbum, Doukbum vein . . .. .. .. .. 221

Poor character of the ore deposits due to the absence of some ore-producing principle in the enclosing rocks . . . . . . . . . . . . . . „

Of lead ores being found in the lower beds situated at great depths below the surface — hopeless except under very peculiar conditions . . . . 222

Of the High Coal Cleugh vein . . . . . . . . . . . . . . „

Scaleburn vein, contrasted with Grassfield veins . . . . . . . . 223

Of the Caple Cleugh and Middle Cleugh veins . . . . . . . . . . 224

Of the Black Ashgill cross vein . . . . . . . . . . , . . . 225

Of the Guddamgill Burn cross vein

Of the Browngill sun vein . . . . . . . . . . . . . . . . 227

That lead ore be deposited in the lower beds, it is necessary that the conditions of hydrous agency be intensified . . . . . . . . . . . . 228

Nothing resulting from the inquiry to support the theory of the sublimation

of the metals Variation in the richness of lead-ore deposits depending upon the character of the enclosing rocks .. .. .. .. .. .. .. __ 229

CHAPTER XI.

OP THE DEPOSITION OP METALLIC OBES IN VEINS THAVEESING CLAY-SLATE AND GBANITE HOOKS.

No exception to the uniformity of Nature's laws.— Veins in granite and clay-slate must be cquaUy subject to hydrous agency as those in the Mountain Limestone . . . . . . . . . . . . _ „„„

Eiohest mines in decomposed granite . . . . . . . , oqi

Metallic ores sometimes found in the joints of the granite . . . , 232

CONTENTS. xix

PAGE

Probable conditiona of its deposition . . . . . . . . . . . . 235

Association of dissimilar rocks . . . . ■ • . . . , . . . . „

Gold, where found 236

Its formation connected with a closer relation fo the atmosphere than that

oflead,&c 237

Silver mines of Potosi . . . . . . . . . . . . . . • • „

The intruded rock may in some instances have been the source from which

the metallic ore was derived .. .. .. .. .. .. .. 238

And the junction a passage for percolating fluids . . . . . . • • „

Depth below the sea of some metallic ore deposits in the south. — How effected 240

CHAPTER XH.

CONOLUDING EEMARKfi.

Lead or its elements must form a component part of the rocks of Alston Moor 242

The inquiry would be simplified should lead be detected in the rooks . . „

Possibility of metals being formed by chemical combination . . . . ■ . „

Hypothesis of Sir H. Davy 243

Ammonia detected in the waters of the English Channel . . . . • ■ ,,

Lead may exist in sea-water . . . . . . . . . . . . . . 244

Silver and copper detected in sea-water . . . . . . . . . . • . ,,

Analyses of the different parts of the Great Limestone, &c. desirable . . . . „

Not likely to throw additional light upon the composition of metals . . . . 245

Sulphide of lead probably never deposited very near the surface . . . . „

Probably now in the course of deposition in the veins of Alston Moor . . 246 If due to hydrous agency, the upper parts of the veins must have been first

Supposed recent deposition of lead ore in Tyne Bottom flats . . . . . . „

Glossary .. : 249

LIST OF ILLUSTRATIONS.

'" I. Section of the Mountain Limestone To face Pa^ 17

'-' n. Section of the Strata at Tees-side Mine .. .. „ 18

" ni. Section of the Strata at Fallow Field Mine . . . . „ 19

^ rV. Section on the Penine range of mountains . • . • „ 21

ti^ V. Nentforce .. .. .. •■ •• ■• ■• ■• Frontispiece

t- VI. Ashgill Force To face Page 41

I— VII. Sections across the Vale of the Nent .. .. .. „ 74

L~ Vni. Plan of the Middle Oleugh veins „ 81

^ IX. Piano-section of Eampgill Vein . . . . „ 103

•— X. Sections of Bast and West Veios .. .. .. „ 116

■— XI. Section of a cross vein . . .. .. .. .. „ 118

1— XTT. Section of a mountain, showing a position of strata unfavourable to the percolation of fluids . . . . . . „ 119

i-XIII. Section on the line A. B., Plate XIV „ 135

i- XIV. Piano-section of SmaU Oleugh Flats „ 136

I- XV. Ashgill Field Flats „ 137

■--XVI. Sketch of a portion of Handsome Mea Cross vein, and section of Cowper DJke Heads vein . . . . . . „ 144

'— XVn. Section across Carrs and small Cleugh veins . . .. „ 166

— XVin. Section showing dislocations of the strata by cross veins on

the north side ;of GiUgill Burn .. .. .. „ 175

t- XIX. Section showing ditto near Guddamgill Burn . . „ 180

■- XX. Section of Nentsberiy Haggs Sun vein . . . . „ 182

1- XXI. Cross Section of Browngill vein . . . . . . „ 202

^ Map of the Mining districts of Alston Moor . . At the end of the Volume.

Introduction

It is mainly owing to the vast stores of coal and iron, and the hardy industry and mechanical ingenuity of her sons, that Great Britain has attained such an exalted position among the nations. Her greatness is more especially dependent upon the production of coal, as a motive power, and also as an agent in the reduction of the yarious ores of iron and other metals : for however rich and abundant these may be, they are useless until reduced to a pure metallic state, which is now almost entirely effected by the heat derived from the combustion of coal. Without a plentiful supply of iron for tools, machinery, railroads, and implements of war, it is scarcely probable, that the ingenuity and industry of the inhabitants could support the high position she now occupies, or prevent her from sinking to a second or even to a third rate power. It has been well remarked, that it can only be after the exhaustion of the last coal-field of our country that the apocalyptic New Zealander will sketch the ruins of St. Paul's.

The tin, copper, and lead mines of the country are secondary in importance only to those of coal and iron. The investigations of geologists during the last fifty, years, have, by assigning limits to the various coal-fields in different parts of the country,

2 INTRODQCTION.

taught the miner to search only in certain localities and among strata occupying a certain position, and thereby the hazard of mining for coal has been lessened. It was probably the art of mining for tin, copper, &c., that gave birth to the science of geology : so little has geology, however, yet effected towards estabKshing a science of mining for these metals, that it was lately stated by an eminent mining engineer, " That there were no greater facilities for ascertaining the productive character of a mine now thap formerly. The difference was simply in improved machinery. Our knowledge was not greater than that of our forefathers." * This, doubtless, is substantially correct ; indeed my impressions are, that mining for lead in Alston Moor is a more hazardous undertaking now than formerly. Without fundamental principles, one mining agent recommends a trial to be made, which another rejects as unworthy. Consequently, should there be fands at command, and a sufficient period of time allowed to elapse, no portions of the veins or lodes are left untried, and practically, the art of mining has degenerated into a mere trial-all system.