NAPA CONSOLIDATED MINE. 



357 



the Manzanita was in tlie liangiiig wall. Tliesc clianibers are true impregnu 

 tions in the soft sandstone. When tlie tenor of the rock is only 1 or 2 per 

 cent, of quicksilver, the cinnabar is hardly visible on a fractured surface, but 

 when such rock is bruised a red stain appears. The color in the pick-marks 

 in such cases is regarded as a trustworthy guide to the value ol the ore. 



on mfts:netic northea.st and aouthwest lioe tlirougb the 

 I'ciiisolidated mino. Scale 400 feet to 1 iiub. 



nrliiogs of the Nap.l 



The two veins of tliis mine answer to " rake veins," while the adjacent 

 chambers correspond to " pipe veins," at least as these terms are defined 

 by von Ootta. Pyrite as well as cinnabar impregnates the walls to some 

 extent. No hot water or sulphur gases enter this mine. 



Cross-section. — Tlic accouipanying diagram (Fig. 14) illustrates the charac- 

 ter of these veins, l)ut portions of the ground were inaccessible, and it does 



