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University of California Publications in Geology [Vol. 10 



pyrite, sphalerite, and galena. The relation of the ore to garnet rock 

 and limestone in this deposit is clearly shown by Prescott in the 

 illustrations reproduced as figures 2 to 5. 11 Prescott uses these figures 

 to illustrate the occurrence of ore at points where limestone projects 



INTERMEDIATE HORIZON 



Fig. 3. 



" " r s s v , v / / 

 / ✓ ✓ l/- j 



UPPER HORIZON 



Fig. 2. 



Generalized plan of ore chimney at Copper Queen Mine, Velardena, Durango, 

 Mexico. After Basil Prescott, Econ. Geo!., vol. 10, p. 62, 1915. 



ii Prescott, Basil, Some observations on contact metamorphie deposits, Econ. 

 Geol., vol. 10, pp. 55-69, 1915. 



