20 ECONOMIC GEOLOGY 



7. Fluoric gold tellurium. Cripple Creek, Colorado. 



8. Zeolitic. Michigan copper ores. 



STRUCTURE, TYPES OF THE CLASSIFICATION UNDER D 



Fissure veins: San Juan, Colorado. Volcanic stocks: Nagyag 

 and Cripple Creek. Contact chimneys: Judith. Dike replace- 

 ments and impregnations. Bedding or contact planes: Mercur, 

 Utah. Axes of folds: Synclinal basins, anticlinal saddles. 

 Bendigo, Elkhorn. 



E. Meteoric waters. (Surface derived.) 

 (a) Underground. 



1. Veins. Wisconsin lead and zinc. 



2. Replacements. Iron ores, Michigan. Lead, zinc, 

 Mississippi Valley. 



3. Residual. Gossan iron ores, manganese deposits. 

 Virginia. 



(b) Surficial. 



1. Chemical. Bog iron ores, sinters Some bedded 

 iron ores, etc. Clinton ore, New York. 



2. Mechanical. Gold and tin placers. California, 

 Alaska. 



F. Metamorphic deposits. Ores concentrated from older 

 rocks by metamorphism, dynamo or regional. 



What Constitutes a Mine? (1) In the broadest sense a mine 

 may be said to consist of a body of ore sufficiently large and 

 rich to pay for the original purchase price of the property, all 

 costs of mining, transportation, reduction plant, together with 

 a large percentage of interest on the investment. 



(2) In determining what constitutes a mine, it is necessary 

 to consider each item of possible expense chargeable against 

 the property, all physical and geological conditions, and such 

 ore bodies as are developed, together with their bearing upon 

 future ore bodies. 



(3) The situation of property is exceedingly important. 

 In this connection it becomes necessary to consider availability 

 of water, for power, for the treatment of the ore, and for the 

 removal of slimes; fuel as a source of heat, and as a source of 

 power; and timber for the shafts and underground workings. 

 It is necessary to consider the accessibility of property both 



