A Study of the Magmatic Sulfid Ores

Front matter

Google to make the world's books discoverable online.

It has survived long enough for the copyright to expire and the book to enter the public domain. A public domain book is one that was never subject

to copyright or whose legal copyright term has expired. Whether a book is in the public domain may vary country to country. Public domain books

Part I. Discussion Of The Bearing Of Magmatic Dif- Ferentiation On Ore Segregation ... 9

Review of the current theories of magmatic differentiation; Theories favored by us ; Problems to be investigated ; Methods of investigation ; Microscopic investigation; Conclusions from our microscopic investigations ; The evidence on which the above conclusions are based ; Replacement phenomena in the magmatic ores; Alteration and later rearrangement in magmatic ores; Absence of pneumatolytic and hydrothermal alteration during ore deposition; Magnetite-ilmenite magmatic ores; Euhedral magnetite formed at a late magmatic stage; Other accessory minerals of probable late magmatic origin; Stages recognized in the formation of magmatic ores.

PART 11. DESCRIPTION OF THE VARIOUS DEPOSITS

OF THE MAGMATIC ORES

GROUP I. THE NICKEL- AND COPPER-BEARING PYRRHOTITIC DEPOSITS

Sudbury, Canada .* ^^

Geology ; Structure of the ore bodies ; Microscopic descriptions ; Origin of the Sudbury ores ; Bibliography of the Sudbury ore deposits. The Alexo Mine» Ontario, Canada ........ 37

Geology; Uglow's conclusions; Microscopic description; Summary; Bibliography of the Alexo ore deposits.

The Friday Mine, San Diego County, California 39

Microscopic description; Summary.

The Golden Curry Mine, Montana 4^

Geology; Microscopic description.

Prospect Hill, Litchfield, Connecticut 43

Knox County, Maine 44

Mountain, Wisconsin 44

Other Pyrrhotite Deposits in the United States 44

iNsizwA Range, East Griqualand, South Africa 44

Geology ; Petrography and mineralogy ; Discussion of Vogt's conclusions ; Summary ; Bibliography of the Norwegian deposits.

PAGB

Other Eusofean Occurrences 54

Sweden; Baden, Horbach, and Todtmoos, Germany; Sohland and Sweiderich on the boundary between Saxony and Bohemia.

GROUP II. THE MAGMATIC CHALCOPYRITE-BORNITE DEPOSITS

OoKiEP, Namaqualand, South Africa 56

Geology; Microscopic descriptions; Summary; Bibliography of the Ookiep deposits.

Engels Mine, Plumas County, California 61

Geology; Microscopic descriptions; Summary; Bibliography of the Engels ore deposit.

REMARKS ON CERTAIN OTHER DEPOSITS THAT HAVE BEEN CLASSIFIED

AS MAGMATIC

Pyritic Deposits 65

Magnetite-Ilmenite Deposits 67

Other Magmatic Iron Ores 67

Chromite Deposits 68