SMITHSONIAN EXPLORATIONS, I929 45 



On the floor of Death Valley is an extensive accumulation of salt 

 and other minerals. We made excavations in this area to determine 

 the mineral character of the salt. Saturated brines are found imme- 

 diately below the surface and in the " blow " holes in the salt crust 

 we found fine groups of halite crystals. 



After the completion of the work in Death Valley we proceeded 

 to the Calico Hills, a brilliantly colored range of mountains lying 

 immediately north of the town of Yermo, San Bernardino County, 

 California. Borax has been produced here in important quantities, 

 but the old camp is now fallen into ruins and we made our camp in 

 a dugout in the clay walls of the canyon. Since the mines have been 

 abandoned for some years and have caved in, our work was confined 

 to the surface exposures and shallow openings. The ore was entirely 

 colemanite, much of it in the form of hollow^ spheres lined with 

 limpid crystals. Light blue crystals of celestite, a sulfate of strontium, 

 are found in these geodes, and with the colemanite form striking 

 specimens. 



Our next locality was the new l:orax mines near Kramer. Cali- 

 fornia, now the only locality where l)orax is mined on an extensive 

 scale. These mines are extraordinarily rich, sufficient borax for 

 several centuries at our present rate of consumption being already 

 available. The ore is pure sodium liorate or borax and contains much 

 kernite, a newly discovered borate of sodium. These mines, to- 

 gether with the chemical plants at Searles Lake where borax is 

 obtained in the process of recovering potash from the lake brines, 

 supply the entire world with borax. Shafts driven to a depth of 

 500 to 1,000 feet reach the borax bed, from which drifts leading in 

 various directions penetrate the ore. These tunnels are driven 

 through masses of solid mineral ; their walls are snowy white with 

 borax or glistening with icy kernite. 



We visited other borax mines including those of Lang. California; 

 White Basin and Callville, Clark County, Nevada ; and the Chetco 

 River, Southern Oregon. 



Besides these mines of borax we examined a number of the playa 

 or dry lake deposits. These playas are the bottoms of the inter- 

 montane valleys, and having no outside drainage, are the basins for all 

 the salts leached from the encircling rocks. In the early days of the 

 American borax industry this mineral was recovered from these 

 alkali flats. Some of these playas are of considerable extent and 

 contain a variety of salts : sulfates, chlorides, carbonates, and borates 

 of sodium. In the muds that underlie the alkali crust are found 

 large and well developed crystals of the various minerals. To collect 



