228 KEMPS ORE DEPOSITS. 



2.11.07. Apache County is in the northeastern corner. In the 

 southern part of the county gold and silver ores, in veins in lime- 

 stone, associate^, with copper ores, are reported, and some small 

 placers. 



2.11.08. Yavapai County. Gold and silver ores, in quartz veins, 

 in granite and metamorphic rocks. The Black Range copper dis- 

 trict has already been referred to under Example 20e. 



Mohave County. Silver sulphides, arsenides, etc., and alteration 

 products in veins in granite, at times showing a gneissoid structure. 

 Only the richest can now be worked. 



Yuma County. Quartz veins, with silver ores and lead miner- 

 als in metamorphosed rocks (gneiss, slate, etc.), or in granite. 



Maricopa County contains both Paleozoic and Archaean expos- 

 ures. The ore deposits lie mostly along the contact of the two, in 

 granite or highly metamorphosed strata. They are usually quartz 

 veins, with silver ores and copper, lead, and zinc minerals. The 

 Globe district, extending also into Final County, is the principal 

 one. Mention has already been made of it under " Copper," Ex- 

 ample 20c. 



Final County adjoins Maricopa on the south and contains a 

 number of important mines. They produce mostly silver ores, 

 with lead and copper associates, and some blende. The gangue 

 minerals are quartz, calcite, etc., occasionally manganese com- 

 pounds, and sometimes, in the granites, barite. Limestone, slate, 

 sandstone, and quartzite, as well as granite, diabase, and diorite, 

 occur as wall rock. 



2.11.09. Silver King Mine. A central mass or chimney of 

 quartz, with innumerable radiating veinlets of the same, carrying 

 rich silver ores and native silver, in a great dike of feldspar por- 

 phyry, with associated granite, syenite (Blake), porphyry, gneiss, 

 and slates, all of Archaean age. The veinlets ramify through the 

 strongly altered porphyry, and form a stockwork, which furnishes 

 the principal ores. In the region are also Paleozoic strata, whose 

 upper limestone beds are referred by Blake to the Carboniferous. 

 The minerals at the mine are native silver, stromeyerite, argen- 

 tite, sphalerite, galenite, tetrahedrite, bornite, chalcopyrite, pyrite, 

 quartz, calcite, siderite, and, as an abundant gangue, barite. 



Groups of the Kanab Valley, Arizona," Amer. Jour. Sci., iii., XX. 221. 

 " Pre-Carboniferous Strata in the Grand Canon of the Colorado, Arizona," 

 Amer. Jour. Sci., December, 1883, 437. Wheeler's Survey, Vol. III., and 

 Supplement. 



