CONTENTS

PART I
[INTRODUCTION
CHAPTER I

PAGE
THE Score or EcoNoMic GeoLogy AND THE SEARCH FOR ORES 1
Definitions of Mineral, Ore-grade, and Metal, The Sporadic Dis.
tribution of Ores, Prospecting, Structure of Lodes. The
term Reef,

CHAPTER II

THE FORMATION OF DEPOSITS OF USEFUL MINERALS ® .
History of Study of Ores. Structure of the Earth ; its Barysphere.
Source of the Metals in Ores. Ore Formation in Relation to
Igneous Rocks. The Ore Zone, Plutonic, Juvenile, and
Magmatic Waters. Magmatic Ores. Lode Deposition—Hydatogenesis,
 Propylitization, and Pneumatolysis. Lode Structure
and Depth of Ore Formation. Ore Sequence in Depth. Ore
Shoots and Ore-bodies. Efflorescent Minerals. Bedded
Mineral Deposits. Alluvial Ores and Placers. Microscopic
Study of Ores. Chief Mineral Deposits due to Segregation,

PART II
ORE DEPOSITS
CHAPTER IIT

ORES OF GoLD . . .
Gold and its Qualities. Gold in Sea-water, Gold Lodes and Igneous
 Rocks. Classification of Gold Ores— Primary Ores.
Gold-quartz Fissure Lodes, California, Ballarat, Mysore,
Volcanic Fields—Rocky Mountains and New Zealand. Pneumatolytic
 Ores—Cripple Greek and Passagem, Brazil. Iso.
lated Gold-quartz Veins—Saddle- and Ladder-lodes. Impregnations
 and Replacements — Rhodesia, Homestake,
Alaska, and Porcupine. The Goldfields of West Australia.
Secondary Ores—Mount Morgan, Queensland, Alluvial
Goldfields—Placers ; Deep Leads, The Rand Banket.
Morro Velho.

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