STATE AGRICULTURAL SOCIETY. 351 



They vaiy in size from a kernel of corn to the size of walnuts. Manj" of 

 them contain dendritic infiltrations of manganese ox.yd, looking like moss. 

 About a bushel of these stones are raised in one day, and are said to have 

 a market value. A white milky variety, similar to the ahove, and without 

 "fire," is found with magnesite in Mount Diablo Eange, thirt}^ miles south 

 of the mountain. Also in the foothills of the Sierra Nevada, at the Four 

 Creeks. 



PEARL SPAE. 



(See Dolomite.) 



PETROLEUM. 



Abundantly distributed throughout the coast counties from San Diego 

 in the south to Crescent City in the north. The purest and most limpid 

 natural oils have thus far been obtained from the localities north of San 

 Francisco, in Ilumholdt and Colusa Courdies. These oils are green by 

 reflected light, and resemble the best samples from Pcnnsjdvania. No 

 abundantly fiowiug wells have yet been found. In Ilumholdt County 

 there are many springs, giving both oil and gas, and numerous wells are in 

 progress. So also in Colusa County^ at Bear Valley, about twentj'-five miles 

 v.'cst of Colusa, several springs, giving a fine quality of lubricating oil 

 and much gas. Also at Antelope District, nineteen miles west of Colusa. 

 In Contra Costa County^ ten miles from Oakland, there are petroleum 

 springs, and a very superior oil has been obtained from the region of 

 Mount Diablo. In Tulare Counfr/ there is an extensive region where oil 

 and gas springs abound. The localities are numerous in the Counties of 

 San Luis Ohisjjo, Santa Barbara, Tulare and Los Angeles. 



PLATINA. 



AVith iridium and iridosmine, on the coast at Cape Blanco, Southern 

 Oregon. Analysis of a sample of the mixed metals from Port Orford, 

 in eighteen hundred and fifty-four, gave forty-three and fifty-four one- 

 bundredths per cent of platina; 



VROVSTITE.— (Light Red Silver Ore.) 



In the veins about Austin, Lander County, Nevada, xitthe Daney Mine, 

 and occasionally in the ore of the Comstock lode. 



PYEARGYRITE— (i)ar7^ Red Silver Ore') 



(See Eubt Silver.) 



PYEOLUSITE. 



Eed Island, Bay of San Francisco, in vein or bed 3' to 4' wide, in the 

 metamorphic jaspery shales — the " prasoid" rocks. This is a remarkably 

 pure ore of manganese, and has been extensively mined for shipment. 



PYEOPIIYLLITE. 



Occurs in the gold region ; locality not known. }• 



