BETWEEN WESTON AND MIKE FAULTS. 237 



])eculiar occurrence has been found, nor can it be hoped for until work on 

 tlie now abandoned shafts shall be resumed. 



The ui)throw of the Breece fault is to the north, and apparently reaches 

 a maximum at its eastern end, where it is estimated at about 500 feet. 



Breece Iron mine. — The Breece Irou mine, which is situated on the western 

 slope of Breece Hill, overlooking Adelaide Park, has a remarkable deposit 

 of red hematite, mixed with magnetite, which occurs at the contact of the 

 main sheets of White and Gray Porphyries. Its ore is found at the surface 

 in two bodies, having a maximum thickness of nearly thirty feet each, the 

 lower of which is underlaid by White Porphyry, while, between it and the 

 up})er body, which is apparently an offshoot from the main body, is a sheet 

 of decomposed porphyry which has certain resemblances both to the Pyri- 

 tiferous and to the Gray Porphyry. This deposit is apparently due to the 

 oxidation of a mass of iron p3rites, which were brought to their present po- 

 sition in solution in a similar manner to the other ore deposits of the region. 

 Indications of iron are found along the contact line between the White and 

 Gray Porphyries, to the eastward, but as yet no considerable bodies of iron 

 have been developed. 



West of the Breece mine, the Superior and Mountain Boy, on the ridge 

 connecting Breece and Yankee Hills, have also struck a considerable body 

 of iron between the Gray and White Porphyries, dipping north. This may 

 be a continuation of the Breece Iron body, the intermediate portion having 

 been removed by the erosion of the head of Stray Horse gulch, which has 

 brought to the surface the White Porphyry underlying the Gray. On the 

 other hand, while tlie Breece iron is an anhydrous red hematite, the mate- 

 rial developed in these shafts consists of brown hematite and bluish-gray 

 chert, the usual replacement material of Blue Limestone, for which reason 

 the outcrop is indicated on the map by the color of that formation. The 

 Theresa (K-57)shaft, to the northeast, finds shales impregnated with pyrites 

 at the contact of the two porpliyries, at a depth of 325 feet. 



AREA NORTH OF BREECE FAULT. 



The line of Mike fault, if continued northward, would pass through an 

 anticlinal fold, whose crest reaches from the north slope of Yankee Hill to 



