346 RESOURCES OF CALIFORNIA. 



Gypsum is found at numerous points in the coast moun- 

 tains, but not in large bodies ; and the name of the Alabaster 

 Cave, in El Dorado County, indicates the material of its sides. 



Clay, valuable for stoneware and fine brick, is obtained at 

 Michigan Bar, and near Antioch. 



There are alum springs at the Geysers and near Owen 

 Lake, and banks of clay containing a strong taste of alum 

 have been noted in Santa Clara and Calaveras Counties. 



Diamonds have been washed out from the placers at many 

 points on the slopes of the Sierra Nevadas ; but they have 

 been too small and too rare to justify hunting for them as an 

 exclusive or as amain occupation. The best place for them 

 so far has been Cherokee, Butte County, where a deep stratum 

 in a dead river, covered by the Oroville Table Mountain, con- 

 tains them. 



Opals are abundant in a stratum near Mokelumne Hill, but 

 they are of a dull lustre and worthless quality. 



Hydraulic lime, fit for cement, occurs in seams in the meta- 

 morphic sandstone, north of Mt. Diablo, and there is enough 

 of it about Benicia to keep a mill going. 



A bed of plumbago, or graphite, near Columbia, was 

 worked in 1867, but has been abandoned as unprofitable. 



Chromic iron is exported from Del ISTorte and Sonoma Coun- 

 ties, and an ore of manganese has been dug in considerable 

 quantities in Red Rock. 



Salt springs are found in Shasta County. 



Deposits of borate of lime, carbonate of soda, and borate 

 of soda, cover the dry beds of numerous ponds east of the 

 Sierra Nevada ; and some of them promise to have a high com- 

 mercial value for the production of borax. 



A small lake, without an outlet, east of Clear Lake, is a 

 weak solution of borax. 



Steatite, or soapstone, valuable as a substitute for fire-brick, 

 exists in extensive layers in El Dorado County, which has 

 also beds of silicious earth, or fine grit, valuable for polish- 

 ing. 



